Disruptive Manufacturing of Oxide Dispersion-Strengthened Steels for Nuclear Applications: Advances, Challenges, and Future Prospects

Abstract

Oxide dispersion-strengthened (ODS) steels are emerging as leading candidate materials for next-generation nuclear reactor components due to their exceptional resistance to creep, fatigue, and irradiation, combined with high strength at elevated temperatures. This paper investigates the microstructural mechanisms underpinning these superior properties, with a particular focus on the critical role of nano-oxides in enhancing performance. Various manufacturing techniques, including powder metallurgy and additive manufacturing, are reviewed to assess their impact on the structural and mechanical properties of ODS steels. Recent case studies on their application in nuclear environments highlight the potential of ODS steels to significantly extend component longevity without necessitating major reactor redesigns. Nevertheless, further research is necessary to assess their reliability under extreme environmental conditions and to determine optimal, scalable manufacturing processes for large-scale production.

1. Introduction

ODS steels are versatile materials with applications across various industries, but their utility is particularly critical for nuclear reactors and associated structures. These materials offer the potential to endure the harsh operating environments of nuclear systems, making them essential for next-generation reactor designs. These steels can be introduced as the primary material for fuel cladding in boiling water reactors, structural components, fuel cladding in Gen IV reactors, and breeding blanket structures in fusion reactors [1].

ODS steels exhibit remarkable thermal stability, enabling them to withstand extremely high temperatures without significant degradation [2]. For ODS steel applications, high temperatures are considered to be any operating temperature within the range of 550 °C to 700 °C. This performance is attributed to the uniform distribution of nano-sized oxide particles within iron-based alloys, hereinafter referred to as “nano-oxides”, which enhances the alloy’s structural integrity. These nano-oxides of various diameters tend to disperse throughout the steel matrix in a uniform manner [3].

Aided by the inclusion of up to 0.35% yttrium, these nano-oxides not only improve thermal stability but also provide exceptional creep resistance, owing to their ability to pin grain boundaries and promote dislocation entanglement [4]. However, a significant challenge in adopting ODS steels on a larger scale lies in their complex manufacturing and processing requirements. Achieving the precise dispersion of nano-oxides demands specialized metallurgy techniques, which complicates production [5]. Notable examples of ODS steels include “14YWT”, a ferritic steel with the composition Fe–14Cr–3W–0.4Ti–0.2Y, and MA754, a nickel–chromium superalloy comprising 77.5% nickel with yttrium nano-oxide dispersoids. These advanced materials exemplify the potential of ODS technology for high-performance applications where high radiation, creep, and fatigue resistance properties are required for long periods. This includes, but is not limited to, fuel claddings for current nuclear reactors, spacecraft parts exposed to prolonged radiation, and structural components within future Gen IV nuclear reactors.

ODS steels offer several advantages for nuclear applications due to their exceptional performance under extreme conditions. These materials maintain high strength at elevated temperatures (>1000 K), with a yield strength that is up to 15% higher and resists degradation for 50% longer than conventional alloys [6]. Furthermore, when exposed to high-energy neutrons, ODS steels exhibit low embrittlement and minimal swelling. Their resistance to oxidation and nitration at elevated temperatures simplifies assembly processes, making them highly desirable for nuclear environments [7].

ODS steels are available with ferritic, ferritic–martensitic, and austenitic matrices, each tailored to specific performance needs. Ferritic grades, which typically contain 8–20% chromium (Cr) and may include aluminum, are particularly effective at resisting neutron irradiation embrittlement and providing oxidation resistance [8]. This makes ferritic ODS steels promising for high-temperature applications such as fuel cladding, acting as a protective barrier for nuclear fuel pellets in reactors.

Despite these advantages, ODS steels also face certain limitations. Their corrosion resistance in hot environments and supercritical water (SCW) is inadequate, necessitating modifications such as increasing the Cr content to enhance performance in these conditions [9]. Despite these improvements, challenges like aging and irradiation embrittlement persist [10]. Additionally, the production of ODS steels presents significant obstacles, including anisotropy in mechanical properties, difficulties in large-scale manufacturing, welding challenges for large structures, and high production costs. Conventional casting techniques have struggled to achieve uniform nano-oxide particle distribution due to the tendency of nano-oxides to accumulate on ingot surfaces. These challenges have spurred the development of alternative methods and materials. Innovations in nano-oxide-doped steels have shown promise for improving production efficiency and material performance [11]. Enhanced toughness, improved creep resistance, and optimized doped matrices are advancing the potential of ODS alloys as sustainable solutions for nuclear applications. For instance, optimized powder metallurgy (PM) and mechanical alloying (MA) techniques have reduced processing time by up to 25%, contributing to enhanced production efficiency [12]. In terms of mechanical performance, nano-oxide dispersion strengthens the matrix, leading to a 30–50% increase in toughness compared to conventional ferritic–martensitic steels [13]. Also, creep resistance is significantly improved, with ODS steels, showing creep rupture lifetimes exceeding 10,000 h at 700 °C under 100 MPa, making them suitable candidates for long-term operation in nuclear reactors [14]. Addressing current limitations, these advancements can pave the way for more reliable and efficient use of ODS materials in critical nuclear components.

The benefits of nuclear technology are well recognized, but equally notorious are the potential dangers associated with its research and application using current and historical methods. Concerns over catastrophic consequences and harmful byproducts have often constrained advancements in this field. However, the advent of new technologies and radiation-resistant materials steadily mitigates these risks, moving us closer to an ideal future of safe and sustainable clean energy. Among these materials, ODS steel has emerged as a strong contender for nuclear reactor systems due to its exceptional ability to withstand the extreme temperatures generated by these systems [15]. One of the biggest obstacles hindering nuclear energy development is the lack of public support due to safety concerns. The superior material properties of ODS steels make nuclear reactors safer, which can increase public acceptance of nuclear reactors as a reliable source of energy.

Recent advancements in manufacturing techniques have significantly influenced the development of ODS steels, reshaping how academia and industry approach research and application in this domain. This review explores these transformative manufacturing processes for ODS steels, delving into their microstructural properties, examining the associated challenges, and assessing their performance in nuclear environments. Through this analysis, we aim to highlight the potential of ODS steels to revolutionize nuclear reactor systems and contribute to a safer, more efficient energy future.

This article carries out a detailed exploration of ODS, with Section 2 focusing on the microstructural properties of ODS steels, with particular emphasis on the positioning of nano-oxides and their influence on the mechanical performance of the material. Section 3 examines various manufacturing techniques used in ODS steel production, outlining their respective advantages and limitations. Section 4 addresses the key challenges hindering large-scale implementation of ODS steels, highlighting areas that require further research and development. In Section 5, the performance of ODS steels under thermal and radiative conditions representative of nuclear environments is evaluated. Section 6 reviews recent advancements and studies in the field, showcasing innovations that have improved the properties and applications of ODS steels. Finally, Section 7 discusses potential future directions, considering how ongoing research could pave the way for broader adoption in advanced engineering applications.

2. Materials and Microstructural Characteristics of ODS Steels

2.1. Composition and Properties of ODS Steels

ODS steel is an advanced alloy with a uniform distribution of iron and nano-oxide particles within its matrix [15]. The inclusion of nano-oxides, such as yttrium oxides and titanium oxides, imparts the material with exceptional thermal resistance [16]. The methods of incorporating these oxides significantly influence their distribution within the steel matrix, affecting the material’s properties. ODS steels are commonly classified into two primary states, ferrite and martensite, based on the relative proportions of ferrite and austenite present. Key elements typically found in ferrite and austenite include chromium, tungsten, molybdenum, nickel, and carbon [15].

Ferrite is a material formed from ferric oxide ($F{e}_x{O}_y$ where x and y are variable) combined with additional rare earth or transition metals. This compound exhibits high magnetic properties and excellent electrical resistance [17]. Ferritic ODS steels are particularly valued in nuclear applications due to their superior resistance to neutron irradiation compared to martensitic steels [18]. Austenite, on the other hand, is a non-magnetic alloy composed primarily of carbon and iron. It is formed at elevated temperatures above the transformation threshold for ferrite. Austenitic materials are notable for their corrosion resistance and are commonly found in stainless steel. This state suits applications requiring high ductility and toughness [16].

The second state, martensite, is produced by rapidly quenching austenite, resulting in a hard, brittle microstructure with high carbon content [19]. While martensitic steels exhibit exceptional tensile strength, their reduced stability often leads to phase transformations when reheated. Additionally, their low ductility makes manufacturing processes like shaping and forming more challenging [16].

The choice between ferritic, austenitic, or martensitic states in ODS steels depends on the desired properties for specific applications. Ferritic ODS steels are often preferred for nuclear reactor components due to their superior irradiation resistance, while austenitic and martensitic steels are chosen for their strength and versatility in other demanding environments.

2.2. Role of Oxide Dispersoids in Enhancing Strength

ODS steels are highly valued for their exceptional creep resistance at elevated temperatures, making them ideal for nuclear applications where materials are subjected to extreme stress levels over extended periods [20]. Creep, the slow deformation of a material under stress, is significantly mitigated in ODS steels due to finely distributed oxide dispersoids introduced through a process known as oxide dispersion. These steels can be manufactured using techniques such as laser powder bed fusion (LPBF) or other advanced manufacturing methods [21].

ODS steels function as interstitial alloys, consisting of a metal matrix (solvent) interspersed with much smaller solute particles, such as oxide dispersoids, that occupy the interstitial spaces in the crystal lattice [22]. Steel itself is a classic interstitial alloy, where carbon atoms serve as the solute, fitting into the gaps of the iron lattice. In ODS steels, the oxide dispersoids act as the solute, reinforcing the steel matrix by introducing lattice distortions [21]. In contrast to substitutional alloys, where solute atoms replace solvent atoms in the lattice, interstitial alloys provide superior strengthening because the solute atoms in interstitial alloys more effectively distort the crystal lattice. These distortions play a critical role in impeding the movement of dislocations, which are the defects in the material’s atomic structure that facilitate deformation [22].

Dislocations are crucial to understanding material strength. They enable slip (plastic deformation) at lower shear stress levels. However, the presence of nano-oxide dispersoids increases the distortions in the lattice, obstructing dislocation motion. This obstruction requires greater shear stress to overcome, thus enhancing the material’s strength and creep resistance [22]. While it might seem counterintuitive, increasing dislocations within the material (via mechanisms such as strain hardening) can further enhance strength, as dislocations impede each other’s movement. A downside of strengthening through increased dislocations is a reduction in ductility, the ability of a material to bend or stretch without breaking [23]. In nuclear applications, ductility is critical to ensure reactor components can deform safely under high stress. This tradeoff can be mitigated through annealing, a process where the material is heated above its recrystallization temperature, held for a set duration, and then cooled [24]. Annealing relieves residual stresses while preserving material strength. Along with this, the annealing process can also improve the long-term stability of the dispersoids by changing their shape into a fully cubical form. Ribis et al. [25] subjected ODS steel to annealing at 1573 K and observed a transformation of the dispersoids into cubical Y₂Ti₂O₇ particles. From there, the interfacial energy of these transformed particles was estimated to be approximately σ = 290 mJm⁻², which is a relatively low value for interfacial energy. The group concluded that this low interfacial energy contributed to an overall reduction in nano-oxide coarsening following recrystallization or grain growth, thus increasing dispersoids’ long-term stability. However, ODS steels require extremely high annealing temperatures, which can degrade their strength. To address this, innovative approaches like two-way cold rolling have been developed to reduce the recrystallization temperature, preventing strength degradation during annealing [24].

Overall, the nano-oxide dispersoids in ODS steels significantly enhance strength by impeding dislocation movement and increasing the material’s creep resistance. Balancing this with ductility through advanced processes ensures that ODS steels remain a cornerstone material for nuclear applications.

2.3. Microstructural Features: Grain Size, Dispersion, and Stability

The characteristics of nano-oxides vary significantly across different ODS steel compositions due to differences in alloy formulation. For typical ODS steels—namely, nanostructured ferritic–martensitic transformable steel (NMS) and nanostructured ferritic alloys (NFA)—the diameters of nano-oxide particles range between 2 and 50 nm. Meanwhile, the grain sizes of the body-centered cubic (BCC) steel matrix in NFA and NMS are typically between 100 and 200 nm, as observed through bright-field scanning transmission electron microscopy (STEM) imaging [26]. As shown in Figure 1 below, the nano-oxides within the steel matrix all have a diameter less than or equal to 20 nm. In the figure, these nano-oxides appear as dark, rectangular spots and have been annotated with red circles for additional clarity. Since the diameter of nano-oxide particles is much smaller than the steel grain size, they can disperse effectively within the steel matrix. However, the total size range of these nano-oxides falls below the smallest grain size by at least a factor of five.

Two key factors affecting the dispersion of nano-oxide within the ferritic matrix are composition and size. The elemental composition of yttrium (Y), titanium (Ti), and oxygen (O) determines whether smaller Y₂Ti₂O₇ oxides or larger Y₂Ti₂O₅ oxides are formed. Stoichiometric conditions, which provide optimal ratios of Y, Ti, and O, are necessary to form the smaller Y₂Ti₂O₇ oxides, leading to better nano-oxide dispersion within the matrix.

Grain size changes in ODS steels can be characterized by the theoretical equation utilized in [28]:

$$\dot{r_i}=M{F}_i$$

(1)

where $\dot{r_i}$ is the rate change in grain radii, M is the thermally activated grain boundary mobility, and $F_i$ is the driving force for grain growth. For a given grain i, the driving force can be expressed as

$$F_i=\left\{\begin{array}{r}-\gamma /r_i-a_i^2/\left(2h\right)+\lambda \mp F_{pin}, -\gamma /r_i-a_i^2/\left(2h\right)+\lambda >F_{pin}\\ 0, -\gamma /r_i-a_i^2/\left(2h\right)+\lambda \le F_{pin}\end{array}\right.,$$

(2)

where γ is the specific grain boundary energy, $a_i^2/\left(2h\right)$ represents the energy density contribution from strain hardening, λ is the Lagrange factor that accounts for the effects of all other grains on grain i, and $F_{pin}$ is the pinning force from oxide particles on the grain boundaries. Since the pinning force in Equation (2) always reduces the magnitude of the force driving grain growth, the theoretical model indicates that dispersed nano-oxides inhibit grain growth in the steel matrix as the temperature, and thus energy density, of the material increases.

ODS steels exhibit significantly improved performance under high-temperature and irradiated conditions compared to conventional austenitic, martensitic, and ferritic steels [29]. The process of helium bubble formation begins with the accumulation of helium within the nano-oxide particle and along the oxide–matrix interface. The initial stage of helium accumulation in and along the nano-oxide provides the necessary local helium density necessary for bubble formation. Once the radius of the accumulated interface helium passes the critical radius threshold, r_b > r_c, a bubble forms on the nano-oxide. At this critical point, the energy in the accumulated helium, E_b, is also lower than the energy in the oxide, E_o, thus allowing for helium to flow out of the oxide and the subsequent formation of a bubble [30]. These enhancements are primarily attributed to the optimal dispersion of nano-oxide particles throughout the steel grain matrix. As Y₂Ti₂O₇ and Y₂Ti₂O₅ oxides disperse interstitially within the steel, they capture free helium (He) atoms in bubble-like structures [31]. These bubbles effectively trap helium, preventing it from interacting with dislocations within the steel matrix. This mechanism significantly extends material longevity by mitigating the adverse effects of helium accumulation [32].

Moreover, the ability of nano-oxide to trap helium reduces the likelihood of grain boundary cracking, a critical failure mode in ODS steels [32]. For instance, an experiment with 14YWT ODS steel containing oxide particles of approximately 10 nm in diameter demonstrated that these nanostructures formed smaller helium bubbles than binary alloys. However, these bubbles trapped a higher number of helium atoms per bubble, effectively minimizing swelling and preventing helium from migrating to grain boundaries, where it could contribute to crack propagation. The microstructural geometry contributes to this mechanism as the high surface area-to-volume ratio allows for effective control over crack propagation and grain boundary damage caused by the helium particles. By mitigating helium-induced microstructural defects, nano-oxide dispersion enhances creep rupture strength and stability at the elevated temperatures typical of nuclear reactors.

The bubbles formed by nano-oxide also play a secondary role in enhancing the stability of ODS steels by reducing defect concentrations within the matrix. These bubbles act as “sinks” for adjacent displacement damage defects caused by radiation [33]. The capacity of nano-oxide bubbles to store these defects—known as “sink strength”—is a critical factor in determining the material’s ability to self-repair from radiation-induced damage. This sink mechanism is seen in Figure 2 as the adjacent nano-oxides trap the helium atoms. In this figure, the orange boxes represent the nano-oxides, the blue circles represent helium, and the surrounding boxes represent a section of the surrounding steel matrix. Having distributions of nano-oxides such as these throughout the ODS steel allows for the effective mitigation of defects and microstructural damages. By lowering the concentration of defects and damage in this manner, the structural stability and resistance to nuclear irradiation effects are significantly improved [33].

Thus, the finely dispersed nano-oxides in ODS steels not only enhance strength and creep resistance by trapping helium and mitigating grain boundary damage but also contribute to overall material stability by reducing defect concentrations. These properties make ODS steels indispensable for high-temperature, radiation-intensive environments such as nuclear reactors.

3. Disruptive Manufacturing Techniques for ODS Steels

3.1. Advanced Powder Metallurgy Methods

To meet the stringent requirements of next-generation nuclear reactors, innovative manufacturing techniques must be developed for producing structural components. Among these, advanced PM is a promising approach due to its precise control over the microstructure and chemical composition of ODS steels. When paired with MA, PM not only enables strain hardening but also reduces the average grain size [35]. This combination, along with improved oxide dispersion throughout the steel matrix, makes them suitable for nuclear reactor environments.

The two primary powder production methods in advanced PM are high-energy and two-stage ball milling. Following powder production, consolidation techniques such as spark plasma sintering (SPS) are employed to shape the material into the desired geometry [36,37].

3.1.1. High-Energy Milling

High-energy milling is an efficient method within powder metallurgy for MA. It involves subjecting metal powders to high-speed milling under an inert atmosphere at room temperature for extended durations. This process induces lattice distortion, elongating the structure along specific axes and facilitating nano-oxide movement within the Fe matrix. A schematic diagram of the motion of powder and balls in a jar during high-energy ball milling is given in Figure 3.

Another product of the high-energy milling process is the noticeable reduction in average grain size when compared to a baseline steel sample. In the study carried out by M. Torralba et al. [36], average grain size decreased from 17.4 μm to 8.2 μm as a direct result of the high-energy milling process. This reduction in average grain size improves performance of ODS steel in high-temperature environments. The increased interstitial positions and uniform dispersion of oxides result in improved tensile strength and other mechanical properties of ODS steels at elevated temperatures [39]. However, high-energy milling also increases the density of dislocations in the crystal structure, which can lower the stress threshold for slip-plane movement. To mitigate this, post-processing techniques such as SPS or annealing are necessary to reduce the dislocation density while retaining the desired nanostructures.

3.1.2. Two-Stage Ball Milling

Two-stage ball milling, combined with SPS, enables the production of austenitic ODS steels with enhanced mechanical properties and reduced dislocation density. The first stage involves mixing metal powders with nano-oxides to ensure uniform dispersion within the ferritic matrix. The second stage introduces a stabilizer that facilitates the phase transformation from ferrite to austenite. This phase transition is essential, as austenitic steel powders tend to adhere to milling tools during MA, leading to reduced yield and process inefficiencies [40].

3.1.3. Spark Plasma Sintering (SPS)

Once the austenitic ODS steel powder has been prepared, it undergoes consolidation via SPS, which uses a die and direct current. Compared to traditional sintering techniques, SPS offers significant advantages, including higher powder densification at lower temperatures and shorter processing times. These parameter reductions minimize grain growth during the SPS process that occurs as a result of the elevated temperature used for sintering. A basic schematic of the SPS system is given in Figure 4.

As shown in [42], an increase in sintering temperature from 950 °C to 1000 °C resulted in an increase in average grain size from 0.84 ± 0.48 μm to 1.07 ± 0.72 μm. This means that a minimization of sintering temperature will reduce average grain size in the ODS steel and improve high-temperature performance above 850 K after sintering. These benefits yield ODS steels with superior strength and ductility while maintaining energy efficiency. To quantify the benefits of SPS, deJong et al. [43] compared ODS steel produced using SPS with ODS steel produced using hot isostatic pressing (HIP), hot extrusion (HE), and HE with friction. In both the yield strength and ultimate tensile strength datasets, the ODS steel produced with SPS generally exceeded the strength of the ODS steels produced with HIP and HE with friction at temperatures lower than 700 °C. However, the strength of the SPS sample fell below that of the HIP sample at temperatures above the 700 °C threshold. Along with this, the SPS sample was consistently below the ODS steel produced with HE across all temperatures for both yield and ultimate tensile strength. This means that relative to conventional consolidation methods such as HIP and HE, SPS offers the trade-off of a lower processing temperature, higher energy efficiency, and shorter production time in exchange for slightly lower yield strength and ultimate tensile strength. However, these differences in mechanical strength reduce in size as the ODS steel samples approach the higher temperatures typically found in nuclear reactor environments.

3.1.4. Flash Sintering and Microwave Sintering

The sintering process can be further enhanced by increasing power dissipation and reducing discharge time, transitioning from SPS to flash sintering (FS). FS allows for even shorter sintering times but poses challenges when applied to metals due to their high electrical conductivity and susceptibility to thermal runaway. Since FS utilizes similar fundamental principles as SPS, grain growth is expected to occur as the material reaches sintering temperature. However, because discharge and sintering times are reduced in comparison to SPS, the average grain size can potentially experience a smaller increase and better maintain the material properties of the ODS steel at temperatures above 850 K.

Microwave sintering is a potential solution to these challenges, as it accelerates densification and minimizes tooling-induced thermal runaway effects [44]. While SPS remains a reliable method for powder consolidation, FS and microwave sintering represent promising advancements for the rapid manufacturing of ODS steels. Figure 5 shows a schematic of FS and microwave sintering processes.

3.2. Mechanochemical Processing and Cryomilling

Mechanochemical processing is a versatile method for fabricating ODS steels, enabling the transformation of unstable oxides into strength-enhancing nano-oxides. In this process, oxides such as CuO and Fe₂O₃ embedded within the Fe matrix decompose into oxygen and interstitial metallic solutions. Through severe plastic deformation, these metallic byproducts dissolve and exit the matrix. The liberated oxygen then reacts with other metallic elements, such as titanium and zirconium, forming stable oxides. These stable oxides act as grain boundary pins, preserving the desired microstructure and preventing grain growth [47]. By facilitating the creation and uniform dispersion of nano-oxides, mechanochemical processing enhances the high-temperature mechanical properties of ODS steels.

Cryomilling, a form of ball milling conducted at cryogenic temperatures, addresses the challenges of heat generation during mechanical alloying [48,49,50]. Room-temperature milling generates significant heat, which can induce non-uniform grain growth and result in a weaker, bimodal microstructure in ODS steels. Cryomilling mitigates these issues by suppressing heat buildup, enabling the formation of finer grains and uniform dispersion of strengthening oxides [51].

Despite these advantages, cryogenic temperatures can adversely affect the mechanical properties of ODS steels. As shown in

Table 1. Temperature-dependent fracture toughness of ODS steels produced at different milling temperatures. Adapted from [52].

Operating Temperature (°C)	Fracture Toughness with Room-Temperature Milling (MPa$\sqrt{\mathbf{m}}$)	Fracture Toughness with −150 °C Milling (MPa$\sqrt{\mathbf{m}}$)
25 (Room Temp.)	60	40
300	80	35
500	55	20
700	72	38

, cryogenically milled ODS steels exhibit lower fracture toughness than their room-temperature-milled counterparts. This reduction is attributed to the embrittling effects of extremely low temperatures, which increase porosity within the matrix and reduce ductility.

Precise control of the milling temperature during cryomilling is essential to achieving optimized mechanical properties at the elevated temperatures encountered in nuclear reactor operations. Balancing the benefits of grain refinement and oxide dispersion with the risks of embrittlement is critical to producing high-performance ODS steels tailored for demanding applications.

3.3. Additive Manufacturing (3D Printing) of ODS Steels

Additive manufacturing (AM) offers a compelling alternative to traditional HIP for consolidating steel powders after alloying. Among the various AM techniques, Laser Powder Bed Fusion (LPBF) and high-speed laser cladding (HSLC) are the most promising methods for producing ODS steels. Both processes enable rapid powder consolidation and efficient distribution of nano-oxides within the ferritic matrix, thereby enhancing the high-temperature strength of ODS steels.

The LPBF process employs a high-power, focused laser beam to selectively solidify sections of a metal powder bed, layer by layer, within an inert gas chamber. Successive layers are stacked to create the final ODS steel structure. This process allows for the fabrication of complex geometries with minimal material waste. However, ODS steels produced via LPBF often exhibit inferior tensile strength and mechanical properties compared to those consolidated using HIP [53]. This is primarily due to the coarse grains in the mechanically alloyed powders typically used in LPBF, which hinder the uniform dispersion of nano-oxides [54]. To address these limitations, manufacturers can employ non-conventional powder alloying methods such as TURBULA^® mixing [5] or adopt in situ synthesis techniques to form nano-oxides directly during the LPBF process. In the study conducted Jia et al. [55], an experimental comparison was performed between nano-oxides produced with in situ synthesis and mechanical alloying. To perform this comparison, both mechanically alloyed powder and powder already including Y and Ti particles underwent selective laser melting (SLM) in a chamber with high oxygen partial pressure. The high partial pressure caused oxygen to diffuse into the powder containing the Y and Ti particles, creating in situ reactions between the particles and oxygen. After scanning and imaging the different ODS steel samples, the group concluded that the in situ synthesized nano-oxides had a higher distribution homogeneity and size uniformity. This indicates that in situ nano-oxide synthesis has a strengthening effect on the ODS steel and can serve as a solution to the limitations of the LPBF process. These innovations can improve oxide dispersion and mechanical performance.

In contrast, HSLC offers enhanced capabilities for producing ODS steels with uniformly distributed nano-oxides and superior mechanical properties. HSLC achieves this by leveraging a smaller laser beam diameter, reduced melt pool size, and higher laser velocities, all of which contribute to increased solidification rates. These factors prevent premature cooling and enable optimal nano-oxide dispersion throughout the steel matrix [56]. By combining precise control over material properties with the ability to fabricate complex geometries, HSLC addresses many of the challenges associated with LPBF and traditional manufacturing techniques.

Thus, AM processes, particularly LPBF and HSLC, demonstrate significant potential for advancing the production of ODS steels. While LPBF enables intricate designs, its limitations in oxide dispersion require innovative powder alloying techniques. Meanwhile, HSLC is a robust method for achieving superior thermomechanical properties. Together, these processes position additive manufacturing as a promising pathway for producing ODS steels tailored for high-performance nuclear applications.

3.4. High-Pressure Torsion and Severe Plastic Deformation Techniques

High-pressure torsion (HPT), depicted in Figure 6, involves compressing a small disc or particle between two anvils under high pressure while simultaneously applying shear through the rotation of the lower anvil relative to the upper anvil [57]. This technique is a prominent severe plastic deformation (SPD) method, extensively used for refining the grain structure of ODS steels, thereby enhancing their physical and mechanical properties. HPT enables grain refinement in ODS steels to an ultrafine or nanometer scale, which significantly improves key attributes such as strength, toughness, superplasticity, swelling resistance, fracture embrittlement, and creep rupture resistance at elevated temperatures [58]. By optimizing these properties, HPT offers a promising pathway for improving the performance of ODS steels in demanding environments, such as those encountered in nuclear and aerospace applications.

The conventional production process for ODS steels typically involves labor-intensive steps, including extensive ball milling, canning, degassing, and complex thermomechanical processing (TMP). The batch-by-batch ball milling stage poses scalability challenges due to its high cost, need for precise equipment, and limited operational pressure capacity [60]. In contrast, HPT presents a more streamlined approach but introduces its challenges. One limitation of HPT is its radial dependency on torsion strain, which can result in inhomogeneous hardness distribution across the material [61]. Additionally, oxide stability remains a concern during high-temperature and high-strain operations, as the coarsening or dissolution of nano-oxides may compromise the strengthening mechanisms. Achieving fine microstructural control can be challenging, as non-uniform deformation may lead to inconsistent material properties.

Other SPD techniques explored for processing ODS steels include Equal Channel Angular Extrusion (ECAE), cryogenic rolling, Repetitive Corrugation and Straightening (RCS), and metal alloying. While each method offers unique advantages, they share common challenges, including maintaining the stability of oxide dispersions and achieving uniform deformation to ensure consistent mechanical properties. Thus, HPT and other SPD techniques offer transformative potential for enhancing the properties of ODS steels. However, fine-tuning these methods to address inhomogeneous deformation and oxide stability remains critical for their broader adoption in advanced material manufacturing.

A summary of the previously discussed manufacturing techniques is provided below in

Table 2. Key advantages and disadvantages of ODS steel manufacturing techniques.

Technique	Advantages	Disadvantages	Reference
High-energy milling	Induces lattice distortions and movement of nano-oxides through the steel matrix	Increases dislocation density in crystal structure without further post-processing	[36,39]
Two-stage ball milling	Reduces dislocation density and uniformly distributes nano-oxides	Requires precise control over transition from ferrite to austenite phase between stages	[40]
Spark plasma sintering	High powder densification, lower operating temperature, energy-efficient process	Relatively high discharge and sintering times	[42]
Flash sintering	Shorter discharge time, high powder densification	High electrical conductivity of ODS steel can lead to thermal runaway effects	[44]
Microwave sintering	Accelerated densification, reduced thermal runaway effects, shorter sintering time	Full effects on ODS steels have yet to be properly explored	[62]
Mechanochemical processing	Converts unstable oxides into strength-enhancing nano-oxides	Required usage of severe plastic deformation can lead to inhomogeneous material properties	[47]
Cryomilling	Reduces heat generation, uniformly distributes nano-oxides, can improve fracture toughness	Induces embrittling of material if temperature is too low, leading to worse material properties	[48,51]
Laser powder bed fusion	Creation of complex geometries with minimal waste material	Produces parts with lower tensile strength if paired with coarse-grain powders	[54]
High-speed laser cladding	Smaller laser and melt pool create uniform distribution of nano-oxides; prevents premature cooling	Energy-intensive process, difficult to implement on larger scale	[56]
High-pressure torsion	Nanoscale grain refinement to improve material properties	Radial dependency on torsional strain, leads to inhomogeneous hardness distribution	[57,60]

. The significant advantages and disadvantages of each one are highlighted, thus showing the feasibility of each one for future ODS steel production.

4. Challenges in Manufacturing ODS Steels

4.1. Homogeneous Dispersion of Oxides

Achieving a homogeneous dispersion of nano-oxides in ODS steels is a critical challenge due to particle agglomeration. This phenomenon results in uneven particle distribution, which diminishes the effectiveness of oxides in strengthening the matrix. Clusters of agglomerated oxides act as stress concentrators, increasing the likelihood of crack initiation, reducing material strength, and decreasing ductility. High temperatures, improper mixing techniques, and chemical similarities between materials often contribute to this agglomeration [63]. ODS steels exhibit exceptional resilience to high radiation damage levels (100 dpa or more), making them suitable for high-temperature environments like fission reactor cladding under high fuel burn-up conditions. However, fusion-joining techniques in these applications can exacerbate particle agglomeration, negatively affecting the material’s performance.

To mitigate these challenges, several strategies can be employed to facilitate a more homogeneous dispersion of nano-oxides: (a). Controlled processing techniques: optimizing temperature profiles and ensuring a controlled environment during processing can reduce agglomeration. (b). Surface modifications and coatings: applying surfactants or modifying the surface of oxide particles reduces attractive forces, enhancing particle dispersion. (c). Optimal processing conditions: achieving ideal temperature, pressure, and processing times ensures proper bonding and distribution of oxides within the matrix.

Material compatibility must also be verified as not all matrix materials are suitable for oxide dispersion. The particle size of oxides plays a significant role, with smaller particles having higher surface energy, which increases the likelihood of agglomeration. Controlling particle size is another critical factor in achieving uniform dispersion.

ODS steels, including reduced activation ferritic martensitic (RAFM) steels, face additional challenges, such as low-temperature hardening embrittlement (LTHE). This phenomenon results in irradiation hardening, even at elevated temperatures ranging from 400 °C to 500 °C. Prolonged use at high operating temperatures can cause deterioration due to neutron damage and the accumulation of transmutation-induced gases, such as helium and hydrogen [64].

Despite these challenges, ODS steels possess remarkable mechanical properties. These properties stem from sub-micrometer-sized oxide particles homogeneously distributed in a corrosion-resistant metallic matrix. Advanced techniques like Laser Additive Manufacturing (LAM), a 3D printing process using high-powered lasers to fuse powdered materials, have demonstrated potential in achieving the desired dispersion and enhancing the overall performance of ODS steels [56].

4.2. Control of Microstructure and Grain Growth

Maintaining excellent mechanical properties in ODS steels is crucial for achieving a stable microstructure. Microstructure instability can lead to significant issues, such as reduced strength, increased embrittlement, thermal instability, and material inhomogeneity, all of which compromise safety and functionality.

Table 3. Microhardness results of developed ODS steels. Reproduced from [65], MDPI Metals, open access, 2020.

Composition	Particle Size, P (µm)	Crystallite Size, L (µm)	HV0.2
14AI-Ti-ODS	38	11.94	320
14AI-Ti-ODS-B	73	11.99	345
14AI-X-ODS	38	11.60	425
14AI-X-ODS-B	54	11.40	420

provides the Vickers microhardness test results performed on four different ODS steel compositions. Among these, 14AI-X-ODS exhibited the highest microhardness (X represents a complex oxide). Compared with other commercial ODS Steels (PM2000 with 20% wt.% Cr, around 270 HV_0.2 or GETMAT with 14 wt.% Cr, around 360 HV_0.2), the fabricated compositions were able to achieve hardness values similar to or even higher than the commercial ODS steels [65]. The small differences in microhardness between the ODS steel pairs can be attributed to adding boron. However, the relatively consistent microhardness across each pair may be due to the uniform and high densification achieved through the SPS process. This shows how the process controls the mechanical properties of ODS steels by having a stable microstructure [65].

ODS steels are inherently challenging to manufacture because of the stringent microstructural requirements. For instance, 9Cr ODS steels demonstrate a high yield strength of 929 MPa and an ultimate tensile strength of 1052 MPa at room temperature. However, when subjected to elevated temperatures (around 800 °C), the ultimate tensile strength drops to 156 MPa. Tensile tests conducted in the ferritic state reveal similar trends, with strength and elongation decreasing as the temperature rises. At room temperature, dislocation activity is homogeneously distributed, but at high temperatures, it localizes near grain boundaries. This phenomenon, known as reduced density dislocation, reflects a decrease in dislocation density within the material’s microstructure [66].

The evolution of microstructure and microhardness in ferritic ODS steels can also be examined under forward and reverse shear strain. Increased hardness during these processes is primarily attributed to grain refinement and the effects of shear strain. The application of shear strain also reduces anisotropy in the material. The presence of fine oxide particles during shearing induces grain subdivision, while the formation of several cell structures with dislocation entanglements further enhances hardness.

Various techniques can influence grain size and distribution, including heat treatment, alloying, and mechanical work. Controlling the microstructure and grain growth is essential in developing ODS steels, as these factors directly affect the material’s strength, ductility, and toughness. By tailoring the material’s grain size and microstructural characteristics, ODS steels can be optimized for specific applications, such as nuclear power generation or other high-temperature environments requiring exceptional strength [67].

4.3. Joining and Welding Challenges

A critical challenge in utilizing ODS steels lies in the process of joining or welding these materials, as conventional welding methods often introduce significant complications. For instance, fusion welding, which involves applying high heat to melt and fuse metal pieces, is unsuitable for ODS steels. The intense heat compromises a substantial volume of the oxide particles, redistributing them unevenly and causing agglomeration [68,69]. This redistribution negatively impacts the structural integrity of ODS steels by weakening their unique ability to withstand elevated temperatures and resist radiation. Similar issues arise with electric arc welding and high-energy fusion techniques, which frequently result in the cracking or coarsening of the material, further diminishing its mechanical properties [69,70].

Among the high-fusion methods, electron-beam (EB) welding shows promising results for ODS. This technique uses a focused electron beam to create small pockets in the material, which are then filled with a liquefied metal to enable adhesion [69,70]. A key advantage of EB welding is its compatibility with the rapid cooling requirements of ODS steels after exposure to elevated temperatures. Additionally, this method significantly reduces the size of fusion and heat-affected zones, even in wide samples. This key property of EB welding makes it suitable for ODS steels as it reduces nano-oxide agglomeration and prevents grain recrystallization in the high-temperature fusion zone. As a result, ODS steel can undergo welding without sacrificing its desirable mechanical properties. However, challenges remain, as the effects of EB welding on nanoparticle configurations are not yet fully understood. Some studies have observed nanoparticle coarsening and slight disruptions in their distribution, though these effects are not consistently observed [69,70]. An example of this is shown in Figure 7 below, where the steel microstructure before and after EB welding is compared.

Table 4. Chemical composition (in wt.%) of the ODS steel before electron-beam welding. Adapted from [69].

Cr	Al	Ti	Y	O	C	N	Fe
18.6	5.5	0.54	0.39	0.09	0.04	0.006	Bal.

provides the chemical composition of the ODS steel prior to EB welding, and Figure 8 provides EDS elemental maps for the fusion zone (FZ) of the welded material.

In both images, the black dots represent the nano-oxides located in the steel matrix. Relative to Figure 7a, Figure 7b indicates that the FZ created by EB welding can lead to an increase in the average diameter of the nano-oxides. While the increase in diameter can lead to improved defect mitigation on a per nano-oxide basis, the FZ also displays a noticeably lower number density. This means that fewer nano-oxides will be interstitially located within the steel matrix. A potential result of this is the inability of the nano-oxides to effectively store defects within all sections of the steel matrix. Thus, EB welding can impact the microstructure–property relationship of ODS steels by increasing the average diameter, decreasing the number density, and altering the irradiation tolerance of the material.

The elemental maps displayed in Figure 8 indicate an absence of larger Ti particles from the FZ that are evident in the base material composition. Along with this, the Y map shows a high concentration of large Y particles on one side of the FZ. These two differences between the original base material and the FZ after EB welding can be attributed to the predominance of Y-Al-O nanoparticles relative to other chemical components. Specifically, the Y, Al, and O particle types are the only ones to undergo significant coarsening during the EB welding process. As a result, these particle types will be the only ones to have larger particles in the elemental maps. However, as stated in [69], the Energy-Dispersive X-ray Spectroscopy (EDS) technique used to produce these elemental maps does not show the larger Al and O particles as clearly as the Y particles.

However, post-processing techniques can be combined with EB welding to mitigate the negative impacts on nano-oxide distributions. In a study by Fu et al. [71], post-production ODS steel was subjected to a heat treatment procedure consisting of normalizing and tempering. This ODS steel sample was then compared to an as-produced ODS steel sample that did not undergo heat treatment. The study found that relative to the as-produced sample, the heat-treated ODS steel had more uniform microhardness properties, a homogeneous distribution of nano-oxides, and a lower dislocation density. This means that for EB welding, post-weld heat treatment strategies similar to the one applied here could restore nano-oxide distributions within the steel matrix and mitigate the degradation of irradiation tolerance induced by EB welding. To address these challenges, solid-state welding techniques are being extensively explored as potentially more suitable alternatives to fusion welding. Among these, friction stir welding (FSW) is a promising method. This technique uses a rotating tool to soften a thin layer at the joint, facilitating the material’s plastic deformation and welding without excessive heat input [68,69]. The usage of plastic deformation allows the nano-oxides to deform through twinning and close any nanovoids located throughout the steel matrix. Along with this, the minimization of heat transfer during the welding process prevents inhomogeneous distributions of nano-oxides. The usage of plastic deformation and reduction in heat transfer to the material allows for friction stir welding to be applied to ODS steels without a reduction in yield strength, creep strength, or irradiation tolerance at high temperatures. Another solid-state method gaining attention is SPS, which involves packing fine powder into the joint and applying a combination of pressure and an electric current. This rapidly melts the powder, forming a strong bond between the joined materials [48,49,70,72].

While these techniques demonstrate significant potential, further investigation is required to better understand their effects on microstructure and nanoparticle configurations. Continued research is also necessary to develop more reliable and efficient joining and welding methods for ODS steels. Advancements in this area will play a crucial role in unlocking the full potential of ODS steels for high-temperature and radiation-resistant applications.

4.4. Scale-Up and Industrialization Challenges

While the demand for ODS steel in nuclear applications is undeniable, scaling up its production to industrial levels presents significant challenges. The currently available steels that can be mass-produced lack the properties required for nuclear use [37]. The production of ODS steel involves a highly meticulous process, including extended ball milling, canning, degassing, and TMP. Among these, ball milling is particularly problematic in a scale-up context, as it is time-intensive, costly, and challenging to apply on an industrial scale. This step is crucial, as it breaks down yttrium oxide into a fine dispersion, ensuring the proper configuration of oxides that provide ODS steel with its exceptional creep resistance and radiation tolerance [60].

To address these bottlenecks, researchers are investigating alternative methods that could either enhance or replace the ball milling process altogether. Among these, SPD and a combination of cold spray (CS), Friction Stir Processing (FSP), and Gas Atomization Reaction Synthesis (GARS) have emerged as promising approaches [60,73,74,75,76]. SPD techniques apply extreme plastic strain to a material, aiming to achieve similar microstructural refinement as ball milling. Examples of SPD methods include high-pressure torsion, equal channel angular extrusion, and friction consolidation [60]. These methods must demonstrate equivalent or superior effectiveness to ball milling to be viable alternatives for large-scale production.

Another potential approach involves CS combined with FSP and GARS. This method uses pressurized gas to deposit a thin layer of metallic powder, produced via GARS, onto the material surface, creating adhesion. While this process shows promise, challenges remain, including inconsistent bonding and the need for additional post-treatment to achieve satisfactory adhesion in some cases [74]. Addressing these scale-up and industrialization challenges is critical for the widespread adoption of ODS steels in nuclear and other high-performance applications. Further research and development are required to refine these alternative methods and establish cost-effective, efficient production processes that maintain the exceptional properties of ODS steels on an industrial scale.

5. Performance and Testing in Nuclear Environments

5.1. Radiation Resistance and Tolerance to Neutron Irradiation

ODS steels are renowned for their exceptional thermal resistance, creep resistance, and radiation tolerance, making them ideal for nuclear applications [77]. These properties stem from their unique composition, characterized by the uniform distribution of oxide particles within the ferritic matrix [69,70,77]. Studies have demonstrated that ODS steels can endure temperatures of up to 650–700 °C without significant degradation in strength [78]. To enhance radiation resistance, ODS steels typically contain low-neutron-activation elements such as aluminum, nickel, cobalt, tungsten, vanadium, silicon, and titanium [79]. These elements contribute to the steel’s mechanical properties by minimizing precipitate formation. Bhattacharya et al. [64] reported the comparison of yield stress and plastic instability stress properties of ODS steels under nuclear irradiation against those of RAFM and conventional steels. Figure 9 plots the ODS steel data, RAFM data, and conventional steel types.

For both plotted mechanical properties, the ODS steels exhibit substantially higher values in comparison to the RAFM and conventional steel types. This trend is exemplified at the higher irradiation level of 100 dpa as the ODS steel MA957 has yield and plastic instability stress values approximating 1750 MPa and 1650 MPa, respectively. These are significantly higher than the values for the steel type that is closest and most comparable, Eurofer97. The general trends highlighted in Figure 9 for mechanical properties indicate that yttrium, oxygen, titanium, and vanadium are critical in providing resistance to irradiation by stabilizing the microstructure. Such compositions make ODS steels suitable for applications such as structural components in fusion and fission reactors, cladding, and ducts [37,78]. Despite their impressive performance, irradiation can induce changes in the oxide particles’ composition and stability.

Research has revealed that irradiation can cause structural defects, alloy dislocations, and grain size alterations in ODS Reduced Activation Ferritic (RAF) steels. For instance, studies by Kurpaska et al. [79] highlighted the disintegration of oxide formations under irradiation. These effects are often accompanied by nanoparticle coarsening and reduced particle density, which can compromise the material’s radiation tolerance [60]. In addition to radiation-induced effects, ODS steels exhibit challenges such as low ductility and limited fracture toughness under specific conditions. Another comparison illustrated in Figure 10 shows how irradiation can reduce the operating-temperature ductility of ODS, RAFM, and conventional steels in a nuclear environment. Figure 10 shows the change in ductile-to-brittle transition temperature (DBTT) as a function of irradiation, which is measured by the number of displacements per atom (dpa) within the material.

In Figure 10, the ODS steel data points are represented by the star points at various dpa values. In each case, the ODS steel has a noticeably larger change in DBTT relative to the RAFM and conventional steels, then a significantly larger change above 40 dpa. However, between the three ODS steels plotted, the ODS-14YWT grade appears to have the lowest change in DBTT and most resistance to irradiation embrittlement. Overall, the trends indicate that as ODS steels are exposed to increasingly higher levels of irradiation, reductions in ductility become more frequent relative to RAFM and conventional steel types as the threshold for transitioning to the brittle state becomes easier to reach.

These limitations underscore the need for continued research to optimize their performance and ensure safe application in nuclear environments. Future advancements in the understanding of irradiation effects and the development of new alloys are critical for enhancing ODS steels’ reliability and broadening their use in next-generation nuclear technologies.

One of the most notable effects of neutron irradiation is the hardening effect attributed to the obstruction of glissile dislocations [80]. This hardening effect can be theoretically represented by the dispersion barrier hardening model (DBH), which describes changes in yield strength and hardness resulting from irradiation [81].

$$\mathsf{\Delta }{\sigma }_y=\alpha M\mu b\sqrt{ND}$$

(3)

$$\mathsf{\Delta }{H}_v=\alpha \mu b\sqrt{ND}$$

(4)

In this model, α represents the strength factor that accounts for the characteristics of the irradiation defects, M is the Taylor factor, μ is the shear modulus of the ODS steel, b is the Burgers vector corresponding to the dislocation, N is the number density of irradiation defects in the material, and D is the average diameter of the defects. Based on Equations (3) and (4) above, the ODS steel will experience increases in both yield strength and hardness in response to increases in size and number of irradiation defects within the material. However, these changes are typically accompanied by an embrittling effect and a decrease in ductility [50].

5.2. Mechanical Properties: Creep, Fatigue, and Fracture Toughness

Creep refers to the gradual deformation of a material under constant stress over extended periods, particularly at high temperatures, which are prevalent in nuclear environments [82]. In such settings, materials are also exposed to irradiation, exacerbating creep through a phenomenon known as irradiation creep [83]. Two primary types of ODS steels that have been extensively studied for their superior creep resistance are 9Cr-ODS steel with a ferritic–martensitic matrix and high-Cr ODS steel with a ferritic matrix. The 9Cr-ODS steel exhibits enhanced tensile strength, improving resistance to creep when compared to conventional ferritic–martensitic steels, which typically contain carbon and ferrite. The high-Cr ODS steel, known for its exceptional thermal and corrosion resistance, reduces creep effects and prevents material degradation, which can otherwise compromise creep resistance [84]. The uniformly dispersed oxide particles in ODS steels play a critical role in mitigating irradiation creep by acting as “sinks” for voids created by nuclear reactor irradiation, thereby preserving structural integrity. By limiting the extent to which voids reduce creep and fatigue strength, the nano-oxides extend the lifespan of the ODS steel material exposed to the harsh environmental conditions of a nuclear reactor.

Fatigue occurs when a material experiences repeated stress cycles, leading to the initiation and growth of small cracks that may eventually cause failure [85]. Nuclear applications frequently expose materials to various stress cycles, particularly thermal stresses, making fatigue resistance a critical property [86]. Compared to non-ODS steels, 9Cr-ODS steels exhibit significantly lower cyclic softening, a type of fatigue where a material loses strength and hardness under cyclic loading [6]. This advantage is attributed to the oxide particles, which inhibit dislocation movement, thereby reducing deformation. ODS steels maintain higher shear stress thresholds by limiting dislocation activity, increasing their resilience to cyclic stresses.

Fracture toughness is a material’s ability to resist the propagation of pre-existing cracks, a crucial property for nuclear applications to ensure the containment of radioactive materials. Unfortunately, ODS steels generally exhibit lower fracture toughness than ferritic–martensitic steels. This limitation arises from their anisotropic behavior, meaning their fracture properties vary depending on the stress direction. This anisotropy can lead to the formation of secondary cracks in addition to primary ones, diminishing overall fracture toughness [87].

5.3. Thermal Stability and Oxidation Resistance

Thermal stability refers to a material’s ability to maintain its mechanical properties when exposed to high temperatures for extended periods. To evaluate the thermal stability of ODS steels, a testing process called thermal aging is employed. In this process, materials are subjected to elevated temperatures, often exceeding their normal operating range, for prolonged durations to simulate extreme service conditions [88]. The duration of thermal aging is crucial, as a material’s response to thermal stress can evolve over time. For instance, in an experiment on 9Cr-ODS steel, the material was thermally aged at 700 °C for 10,000 h. Results showed negligible reductions in hardness and tensile strength, indicating excellent thermal stability. Furthermore, the experiment revealed minimal changes in grain size and distribution, contributing significantly to the material’s ability to retain its mechanical properties under thermal stress [88]. The superior performance of ODS steels during thermal aging is primarily attributed to the embedded nano-oxides, as these particles act as barriers to dislocation movement and inhibit recrystallization, thereby preserving the material’s mechanical integrity under prolonged exposure to high temperatures [88].

Oxidation occurs when materials react with oxygen, forming surface oxides that can lead to corrosion, weakening the material and reducing its ductility [89]. However, certain materials, including ODS steels, can form a protective oxide layer that prevents further oxidation and material degradation. In nuclear applications, particularly in supercritical water-cooled reactors (SCWRs), materials are exposed to extreme oxidation conditions due to water being heated beyond its critical point, where it exists in a supercritical phase without distinct liquid or gas states [66]. For ODS steels to be viable in such environments, they must demonstrate high oxidation resistance. The presence of yttrium oxide nanoparticles in ODS steels is a key factor in their inherent oxidation resistance. These nanoparticles stabilize the material’s surface, reducing its susceptibility to corrosion. Additionally, alloying elements such as aluminum can significantly enhance this resistance, as demonstrated in

Table 5. Oxide layer thickness of various steels after oxidation testing in a furnace at 700 °C for 100 h in air. Adapted from [89].

Material	Oxide Layer (µm)
Al-containing 16Cr-ODS steel	5–10
Al-free 16Cr-ODS steel	25
304 Stainless steel	85

. For example, experiments conducted on 16-Cr ODS ferritic steels demonstrated that aluminum-containing alloys exhibited the highest oxidation resistance when tested at 700 °C for 100 h in air [89]. This improved performance is due to aluminum’s ability to form an immediate protective oxide layer upon exposure to air, effectively shielding the material from further oxidation and preserving its mechanical properties.

5.4. Long-Term Performance Under High Temperature and Stress

In nuclear applications, ODS steels must endure continuous exposure to extreme conditions, including sustained temperatures of 600–650 °C and occasional peaks up to 1000 °C [88]. Additionally, these materials must resist high cyclic stress levels while maintaining their structural and mechanical integrity. To perform effectively in such demanding environments, ODS steels must exhibit a combination of high creep resistance, fatigue resistance, radiation resistance, thermal stability, and oxidation resistance.

ODS steels demonstrate exceptional long-term thermal stability, as evidenced by a study conducted by Zheng et al. [88], where 9Cr-ODS steel showed negligible reductions in strength after 10,000 h of thermal aging at 700 °C. The minimal reductions in strength can be attributed to the lack of recrystallization in the grain structures during thermal aging. Specifically, conventional metals undergo full and local recrystallization when exposed to high temperatures for prolonged periods. This would create anisotropic grain growth within the microstructure, leading to reductions in thermal stability and degraded mechanical properties. However, because the homogeneously distributed nano-oxides within the steel matrix can prevent this recrystallization, ODS steel maintains its stability and mechanical properties at high temperatures. This remarkable stability makes them a strong candidate for high-temperature applications. Moreover, ODS steels display excellent oxidation resistance within a temperature range of 700–800 °C, with 13Cr-ODS steels maintaining their structural integrity for up to 7000 h at 900 °C. However, beyond this threshold, the material failed under prolonged exposure, highlighting the need for further optimization for ultra-high-temperature applications [90]. The creep threshold stress, the stress level below which the creep rate is insignificant, of ODS steels is approximately 56.2 MPa at 800 °C [91]. This high creep resistance, combined with the inherent stability of nano-oxide particles that inhibit dislocation movement and recrystallization, ensures their reliable performance under sustained high temperatures and stress. ODS steels have high long-term thermal stability, oxidation resistance, and creep resistance, which will minimize material failure caused by fatigue, creep, and corrosion. A summary of key properties of ODS steel in nuclear conditions is shown below in

Table 6. Performance matrix comparing mechanical properties of conventional, ODS, and advanced steels under nuclear conditions. For the yield stress, elongation, and swelling values, the irradiation temperature T_irr ranged from 270 °C to 470 °C. Each set value was recorded at the same irradiation temperature. Table adapted from data in [64].

Steel Type	Yield Stress at 100 dpa (MPa)	Vickers Microhardness at 450 °C (HV), ×9.8 MPa	Uniform Elongation at 80 dpa (%)	Total Elongation at 80 dpa (%)	Swelling (%)
ODS-MA957	1700	450	1.00	5.00	0.00
Eurofer97	1300	225	0.30	6.50	0.75
F82H	1190	415	0.25	8.50	0.05

.

The values presented in Table 6 indicate that in comparison to conventional and RAFM steels, ODS steels have improved yield stress, microhardness, and reduced swelling at the high-temperature and irradiation conditions resembling a nuclear reactor. These properties allow ODS steels to operate for longer times without complete failure, permanent deformation, or surface damage. This can improve the safety and efficiency of nuclear reactors by preventing accidents caused by material failure, as well as reducing downtime from maintenance caused by material deformation or failure.

This can improve the safety and efficiency of nuclear reactors by preventing accidents caused by material failure, as well as reducing downtime from maintenance caused by material deformation or failure. However, despite their advantages, ODS steels exhibit relatively low fracture toughness, which can pose challenges in scenarios where crack propagation must be minimized. However, a potential strategy to mitigate the reduction in fracture toughness is by utilizing manufacturing techniques that can raise the initial fracture toughness of the ODS steel. Cryomilling of ODS steels at a controlled temperature allows for improved fracture toughness during elevated operating temperatures. This strategy can prevent the material fracture toughness from going below the threshold which would result in part failure. Another potential solution to the problem of low fracture toughness is the utilization of grain boundary engineering, consisting in the addition of small-scale metalloid particles into a refractory, high-entropy alloy matrix. This process improves the material fracture toughness by replacing contaminants located at the grain boundaries that are weakening the grain–boundary cohesion. As a result, the primary fracture mode changes from intergranular to transgranular fracture. While this process does have the potential to mitigate the limitations of low fracture toughness on ODS steel, more research is necessary to assess process compatibility with ODS steel, find a suitable metalloid, and verify whether the same microstructural mechanisms found in the refractory alloy occur in ODS steel [92]. Nevertheless, their overall performance under extreme conditions, including superior resistance to creep, fatigue, and oxidation, positions them as promising materials for nuclear cladding and other high-stress applications in the energy sector.

6. Current Developments and Case Studies

6.1. Notable Advancements in ODS Steel Manufacturing for Nuclear Applications

Recent advancements in manufacturing technologies have significantly improved the production processes for ODS steels, particularly for nuclear applications. Among these, AM has emerged as a viable alternative to traditional sintering processes. Unlike conventional methods, which require extensive post-processing and machining to achieve the final product, AM enables the direct fabrication of parts with complex geometries in fewer steps. This streamlined production process is illustrated in Figure 11, where AM significantly reduces the number of stages needed to produce components with the desired thermomechanical properties. As a result, AM minimizes production time and lowers the long-term costs associated with ODS steel manufacturing.

However, challenges remain for the full-scale implementation of AM in ODS steel production. A critical issue is the high melt pool temperature inherent in many AM techniques [93]. During the process, the region of melted metal powder, known as the melt pool, often reaches extremely high temperatures. These elevated temperatures can cause the nano-oxides dispersed within the ODS steel to evaporate or coalesce, diminishing or entirely negating the material’s superior mechanical properties [94]. Specifically, a decrease in nano-oxide number density or homogeneity would result in a reduction in the ability of the ODS steel to store irradiation-induced defects and mitigate anisotropic grain growth. However, a solution to this problem facing several AM techniques is the utilization of emerging technologies such as high-speed laser cladding. As stated in Section 3.3, the smaller laser diameter and high laser velocity allow the process to operate with a lower melt pool temperature. This prevents nanoparticle coalescence within the ODS steel, thus maintaining the high yield strength, irradiation tolerance, and creep strength. Addressing this challenge is essential for the widespread adoption of AM in ODS steel fabrication.

Another promising innovation is cold-spray manufacturing, which has gained traction as a potential replacement for traditional methods such as HIP and hot extrusion. In the cold-spray process, ball-milled or cryomilled metal powder is used as feedstock and sprayed onto a substrate at high velocity. This high-impact deposition causes the particles to deform and form a dense, uniform metallic layer [95,96,97]. By using this technique to produce ODS steel cladding and tubing, cold-spray manufacturing avoids the non-uniform deformation and reduction in fracture toughness often associated with conventional methods [98]. In the cost analysis study conducted by Stier [99], the economic feasibility of cold-spray manufacturing was assessed. The study used MCrAlY as the cold-sprayed powder and a mixture of helium and nitrogen as the propellant gas pushing the powder. The economic model for this analysis was constructed by expressing the total cost of CS manufacturing as a function of powder, propellant gas, electricity, and equipment costs. From there, the different costs were rewritten and simplified to express total cost as a function of deposition efficiency (DE), that is, the percentage of sprayed powder that is successfully used, and mass loading ratio (W), which is the ratio of powder mass flow rate to gas mass flow rate. These two parameters are indicative of the total CS time, powder consumption, and gas consumption necessary for a given CS process, allowing them to accurately represent the different costs. The study indicated that the total cost for the CS manufacturing of MCrAlY was minimized as the mass loading ratio and deposition efficiency increased. This makes sense as higher W and DE result in lower gas consumption, reduced powder waste, and shorter manufacturing times. In terms of costs, this translates to lower gas, powder, and electricity costs for a given CS manufacturing process. While the exact monetary values were specifically for the MCrAlY powder, the general trend of total cost was dependent on the CS process itself rather than a specific powder type [99]. Thus, the cost analysis conducted there indicated that ODS steel production using CS manufacturing was feasible if the process had sufficiently high deposition efficiency and mass loading ratio values.

These advancements in manufacturing methodologies, including the refinement of AM and the adoption of CS techniques, are driving the development of ODS steels with enhanced performance. By overcoming current challenges, these methods promise to improve the efficiency, reliability, and long-term viability of ODS steels in demanding nuclear environments.

6.2. Case Studies of ODS Steels in Reactor Components

In 2021, M. Rieth et al. [100] conducted a case study to evaluate the potential of using ODS steel exclusively for the outer wall that would experience the highest heat transfer and neutron loads. In this study, ODS steel plates were fabricated using conventional manufacturing techniques, while the remaining structural components were constructed from EUROFER97 steel. The assembled structure underwent high-heat flux and irradiation testing, yielding results that showed no significant damage to the shielded EUROFER97 steel apart from a localized heat-affected zone. These findings demonstrated that the ODS steel was effective in withstanding neutron irradiation and rapid heat flux, thereby shielding the weaker EUROFER97 material from the harsh nuclear environment. This study highlights the suitability of ODS steels as a promising candidate for next-generation nuclear reactor materials. Along with this, the case study indicates a high degree of compatibility between ODS steels and conventional steels. Specifically, combining the two types of steel into a hybrid system allows for the ODS steel to bear the highest mechanical and thermal loads while the cost-effective conventional steel can withstand basic structural loads. Hybrid systems such as this will allow for faster and more efficient implementation of ODS steels into nuclear reactors.

A more recent case study in Japan focused on the application of ODS steels in the production of fuel claddings [101]. Various geometries and components were fabricated entirely from ODS steel and subjected to experimental testing in high-temperature environments. These tests evaluated key material properties, including yield strength, irradiation resistance, corrosion resistance, and wear resistance. Figure 12 provides a comparison between the wear resistance of the ODS steel and conventional Zircaloy material used for fuel claddings.

To evaluate the wear resistance, sliding tests were performed within the case study on both materials at room temperature, in both air and water, and for various time periods. In each set of environmental parameters, the ODS steel had a noticeably smaller wear depth than the Zircalloy. This implies that ODS steel has a higher wear resistance than conventional materials, making it more suitable for nuclear fuel claddings.

Additionally, an analytical study was conducted to assess the compatibility of ODS steels with existing reactor designs in Japan. Results indicated that ODS steels could maintain their favorable material properties under prolonged high-temperature conditions without necessitating a redesign of the current reactor architecture.

While these findings are promising, the researchers emphasized the need for additional testing in real-world reactor environments to validate the analytical results and ensure reliable performance during long-term operation. These case studies collectively highlight the potential of ODS steels to advance nuclear reactor technologies while also identifying areas requiring further investigation before full-scale implementation.

6.3. Comparative Analysis with Other High-Performance Materials

The exceptional performance of ODS steels in harsh environments positions them as a leading material for nuclear applications, outperforming many high-performance alternatives, as shown in Figure 13. One notable comparison is with ceramics, materials renowned for their resistance to high temperatures and radiation. While ceramics excel in these areas, their brittle nature poses significant challenges, making them prone to cracking under mechanical stress. Additionally, ceramics are difficult to shape and integrate into complex structures due to their inability to be melted and reformed, unlike ODS steels, which offer greater ductility and manufacturability. Similarly, refractory metals and alloys, such as tungsten and molybdenum, demonstrate excellent temperature and radiation resistance. However, these materials also suffer from brittleness, complicating their use in structural applications and fabrication processes compared to the more workable nature of ODS steels [102].

Even metals with favorable properties face limitations when compared to ODS steels. Austenitic stainless steel, for instance, has long been valued in the nuclear and chemical industries for its toughness, ductility, and corrosion resistance. Despite its advantages, this material exhibits several drawbacks. In environments with high chloride concentrations, such as those encountered in spent nuclear fuel, austenitic stainless steel may experience inadequate corrosion resistance. Specifically, while austenitic stainless steels, as welded, can only reach surface micro-hardness values of 200–250 VHN, ODS steels have values in the range of 320–420 VHN. This means that the base ODS steel has higher wear resistance and surface durability than the base austenitic stainless steel, thus making it more suitable for nuclear environments. Furthermore, it is susceptible to radiation-induced swelling and thermal damage at elevated temperatures, reducing its suitability for long-term use in nuclear applications [103].

ODS steels overcome these challenges due to their systematic dispersion of oxide nanoparticles, which enhances their corrosion and thermal resistance far beyond that of traditional austenitic stainless steels. This unique composition ensures that ODS steels maintain their mechanical and structural integrity in demanding nuclear environments, making them a superior choice for next-generation reactor components, such as fuel cladding within Gen IV nuclear reactors.

7. Future Directions and Opportunities

7.1. Integration with Smart Manufacturing and AI

The advent of smart manufacturing and artificial intelligence (AI) is reshaping the production and research of ODS steels, bringing unparalleled precision and efficiency to the field. Cyber-physical systems (CPSs) merge physical processes with computing technology by incorporating embedded computing that allows for feedback control systems. These technologies enable real-time monitoring of both the material during processing and the machines involved in its production. By integrating sensors with AI-driven systems, manufacturers can implement predictive maintenance, identifying potential machine failures before they occur and minimizing downtime [104]. In the case of ODS steel production, AI could be integrated by using it during the mechanical alloying, sintering, and post-processing steps. Specifically, AI would be used for real-time monitoring and predictive control of a mechanical alloying machine to optimize for average grain size and then control sintering temperature to retain the desired nanostructure. From there, the AI-driven system would implement a post-processing step to maximize the yield strength, fatigue resistance, and creep resistance of the material at temperatures above 850 K.

In a study conducted by Deng et al. [105], machine learning (ML) was combined with hot isostatic pressing (HIP) to produce Fe-12%Cr-4.5%Al-2.0%W-0.3%Y₂O₃ ODS steel. From there, the material underwent wedge-shaped hot rolling to simulate the forming process necessary to turn the material into fuel cladding for a nuclear reactor. The ML model was used during the first stage to determine the optimal FeCrAl powder composition and yttrium oxide content necessary to achieve the desired ODS steel properties. After the HIP step, the ultimate tensile strength values of the samples at 25 °C and 700 °C were compared to the theoretical values predicted by the ML model. The ranges of actual sample values were 840–935 MPa for 25 °C and 240–226 MPa for 700 °C, while the predicted values were 877 MPa and 241 MPa, respectively. In addition to this, imaging of the steel samples after wedge-shaped hot rolling indicated that the Y₂O₃ nano-oxides were uniformly distributed throughout the ferrite matrix. This means that the integration of ML and AI into the ODS steel design process resulted in improved oxide dispersion and accurately predicted mechanical properties.

In situ monitoring has been a game-changer for manufacturing processes, as embedded sensors can detect fluctuations in critical parameters such as temperature, pressure, and material flow. These systems can autonomously adjust operations or even halt production to prevent defects, ensuring higher-quality outcomes [106]. For ODS steels, sensors could play a pivotal role in detecting uneven oxide dispersion, an essential factor for the material’s performance. By recording material behavior under various conditions, these technologies also enable more comprehensive research, accelerating the development of ODS steels and similar advanced materials.

Smart manufacturing involves the collection of tools for improved management of manufacturing processes, facilitating data exchange, enabling real-time operational monitoring, and developing systems for both identifying and predicting potential issues. Smart manufacturing methods offer additional benefits, including reduced costs and waste typically associated with traditional trial-and-error testing. One standout approach is AM, a form of 3D printing that constructs products layer by layer. This technique excels at creating complex geometries with minimal material waste compared to conventional methods [107]. LPBF showcases the potential of additive manufacturing as a promising technique. While this process occasionally has porosity defects, AI-driven monitoring, aided by sensors collecting process data, enhances accuracy by providing a comprehensive view of the production process. AM’s ability to precisely control material deposition makes it particularly promising for producing ODS steel components with intricate designs.

Though still in their early stages, smart manufacturing and AI hold immense potential to revolutionize ODS steel development and other materials for nuclear applications. These innovations promise not only greater efficiency and cost-effectiveness but also pave the way for creating next-generation materials with superior properties tailored to meet the demands of extreme environments.

7.2. Prospects for Enhanced Radiation Tolerance

ODS steels represent a highly promising material for applications requiring enhanced radiation tolerance, particularly in nuclear and other extreme environments. Their exceptional radiation damage resistance, robust mechanical properties, and remarkable microstructural stability make them ideal for these demanding conditions.

A key contributor to their radiation tolerance is the presence of finely dispersed oxide particles within the steel matrix. These particles act as traps for radiation-induced defects, such as vacancies and interstitials, effectively immobilizing them and reducing cumulative damage over time. This results in a significantly extended lifespan under radiation exposure [108]. These attributes make ODS steels indispensable for Gen IV nuclear reactor components, where radiation tolerance and mechanical strength are paramount [109].

Beyond nuclear reactors, ODS steels hold promise for a wide range of advanced applications: (a) Fusion reactors: components such as blanket modules are exposed to intense neutron radiation, where ODS steels can provide the necessary resilience. (b) Space applications: cosmic radiation poses a significant challenge for satellites and spacecraft; ODS steels ensure structural integrity in these harsh environments, enhancing mission reliability. (c) Advanced manufacturing: ODS steels’ stability under extreme conditions supports innovations in high-performance manufacturing processes. (d) Medical devices: radiation-resistant materials are crucial for certain medical technologies exposed to radiation during use. (e) ODS steels offer the potential for significant advancement for prefabricated steel structures in construction, where high-temperature corrosive conditions must be addressed. This can be attributed to their high corrosion resistance and thermal stability over extended periods. Shown below in Figure 14 is the total weight change over time of an ODS sample due to corrosion. For this corrosion test, Normal Water Chemistry (NWC) and Hydrogen Water Chemistry (HWC) solutions were used to corrode the steel surface.

All of the experimental data presented in Figure 14 were collected at 561 K or 563 K over periods ranging from half a year to over one year. However, despite these prolonged, harsh environmental conditions, the ODS steel saw limited corrosive weight change. This means that ODS steels could be implemented into prefabricated steel structure assembly, increasing the corrosion resistance and thermal stability of the overall structure. Thus, ODS steels could see future applications in construction for enhancing the lifespan and reliability of prefabricated steel structures.

The prospects for ODS steels extend far beyond nuclear energy, underscoring their versatility and critical importance in radiation-intensive applications. Their unique combination of properties positions them as a cornerstone material for future innovations across industries [110].

7.3. Potential Next-Generation Nuclear Reactors

Next-generation Gen IV nuclear reactors aim to achieve enhanced durability, superior neutron resistance, and greater energy conversion efficiency. To meet these ambitious goals, advanced materials such as ODS steels will play a pivotal role due to their exceptional properties. A key development strategy for advancing these reactors is the use of computational thermodynamics modeling, an advanced technique capable of predicting material behavior under extreme conditions. This approach offers a low-risk yet high-reward pathway by enabling the precise optimization of material properties for reactor environments [111]. Another, higher-risk, higher-reward strategy focuses on metallurgical innovations to minimize degradation caused by neutron irradiation. This includes addressing challenges such as low-temperature hardening and volumetric void swelling, which result from helium and hydrogen generation under radiation exposure. By tackling these issues, researchers aim to enhance the long-term performance of reactor materials.

For future Gen IV nuclear reactors, evaluating the material properties of ODS steels is crucial. Critical parameters include: (a) tensile elongation: ensuring sufficient ductility to prevent catastrophic failure; (b) high-temperature thermal creep resistance: maintaining structural integrity under sustained high temperatures; (c) uniaxial yield strength: providing strength to withstand operational stresses; and (d) Irradiation effects: assessing performance under prolonged neutron exposure.

ODS steels are particularly well suited for reactor components exposed to highly damaging, fast-moving neutrons with energy levels of approximately 14.1 MeV. Their high-temperature performance also supports improved thermal efficiency, further justifying their application in next-generation designs [112]. As reactor designs continue to evolve, ODS steels stand out as an essential material, offering the resilience and efficiency required for future innovations in nuclear energy.

7.4. Policy and Regulatory Implications for Nuclear Materials

The inherently high-risk nature of nuclear reactors necessitates stringent regulations for nuclear materials to ensure safety and prevent catastrophic failures. ODS steels, which are increasingly being considered for use as reactor cladding, fall under such critical regulatory oversight to mitigate risks associated with material failure. Historical nuclear disasters, such as the Fukushima Daiichi accident in 2011, underscore the importance of robust safety protocols. In that instance, cooling system failures caused fuel cladding, similar to the role ODS steels would perform, to overheat, leading to hydrogen buildup, ignition, and the release of massive amounts of radiation [113]. Public apprehension, shaped by this and other infamous accidents like Chernobyl and Three Mile Island, continues to influence policy and enforce stringent standards for nuclear materials. The International Atomic Energy Agency (IAEA) classifies nuclear materials into three safety categories based on the potential consequences of failure: (a) Class 1 materials pose the highest danger if compromised, (b) Class 2 materials present moderate risks, and (c) Class 3 materials have the least potential for harm [114]. A categorization of nuclear materials into each class is shown below in Figure 15.

One of the key regulations governing ODS steels is the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code Section III, Division 5 [116]. This code establishes design criteria for high-temperature nuclear components, including methods for evaluating stress intensity and material integrity under extreme conditions. Complementing this is the U.S. Nuclear Regulatory Commission’s (NRC) Standard Review Plan, which mandates rigorous testing of Class 1, 2, and 3 materials to withstand various scenarios, such as normal operation, design limit conditions, loss-of-coolant accidents, seismic events, and pipe breaks [117]. Regulatory frameworks emphasize that nuclear materials must not only perform reliably under ideal conditions but also endure worst-case scenarios. The lessons learned from past accidents have solidified the necessity of proactive safety measures to maintain public trust and ensure the long-term viability of nuclear energy.

8. Conclusions

ODS steels hold tremendous promise as advanced materials for nuclear applications, due to their exceptional resistance to radiation, creep, fatigue, and oxidation, coupled with superior thermal stability and mechanical strength. These properties make them strong contenders for addressing the stringent demands of next-generation nuclear reactors. However, their widespread adoption depends on overcoming critical challenges, including low fracture toughness, oxide particle agglomeration, microstructural instability, and inefficiencies in current production methods. Advances in manufacturing, particularly through additive manufacturing, cryomilling, mechanochemical processing, and laser-based techniques, offer pathways to address these issues. Innovations in these areas can enhance material uniformity, reduce waste, and accelerate processing times. Computational tools such as AI and thermodynamic modeling help optimize ODS steel through real-time monitoring and adaptive feedback control systems, reducing uncertainty during the manufacturing process. Smart manufacturing through the use of additive-based techniques will also be capable of reducing process risks, cost, and waste. By combining AI and smart manufacturing, ODS steels can be efficiently produced in a cost-effective manner that will allow for more seamless integration into current and future reactors. The most promising future nuclear application of ODS steels will be in Gen IV reactors, where their exceptional high-temperature strength, radiation resistance, and long-term structural stability could enable safer, more efficient reactor designs capable of withstanding demanding operational environments. In addition to this, ODS steels also hold potential for emerging applications beyond conventional nuclear reactors, such as fusion energy systems, space exploration, and high-performance industrial components. However, achieving their full potential requires additional interdisciplinary research to improve manufacturability, refine microstructural control, and validate their performance under extreme conditions. Future research in these fields will be key to obtaining the desired levels of ODS steel performance and utilization in nuclear reactors. In summary, ODS steels are poised to become a cornerstone of advanced nuclear technologies, offering enhanced safety, efficiency, and reliability. Through continued research, innovation in manufacturing, and adherence to stringent safety standards, these materials could play a pivotal role in the transition to cleaner and more sustainable energy systems, solidifying their place in the future of energy and technology.