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Search Results (1,311)

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Keywords = high-entropy alloy

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12 pages, 7595 KiB  
Article
Reactive Sintering of Cemented Carbides
by Victor I. Stanciu, Alexandre Mégret, Anne Mouftiez, Véronique Vitry and Fabienne Delaunois
Alloys 2025, 4(3), 15; https://doi.org/10.3390/alloys4030015 - 25 Jul 2025
Abstract
Cemented carbides are among the primary materials for tools and wear parts. Today, energy prices and carbon emissions have become key concerns worldwide. Cemented carbides consist of tungsten carbide combined with a binder, typically cobalt, nickel, or more recently, various high-entropy alloys. Producing [...] Read more.
Cemented carbides are among the primary materials for tools and wear parts. Today, energy prices and carbon emissions have become key concerns worldwide. Cemented carbides consist of tungsten carbide combined with a binder, typically cobalt, nickel, or more recently, various high-entropy alloys. Producing tungsten carbide involves reducing tungsten oxide, followed by carburization of tungsten at 1400 °C under a hydrogen atmosphere. The tungsten carbide produced is then mixed with the binder, milled to achieve the desired particle size, and granulated to ensure proper flow for pressing and shaping. This study aims to bypass the tungsten carburizing step by mixing tungsten, carbon, and cobalt; shaping the mixture; and then applying reactive sintering, which will convert tungsten into carbide and consolidate the parts. The mixtures were prepared by planetary ball milling for 10 h under different conditions. Tests demonstrated that tungsten carburization successfully occurs during sintering at 1450 °C for 1 h. The samples exhibit a typical cemented carbide microstructure, characterized by prismatic grains with an average size of 0.32 μm. Densification reached 92%, hardness is approximately 1800 HV30, and toughness is 10.9 ± 1.15 MPa·m1/2. Full article
(This article belongs to the Special Issue New Alloys for Surface Engineered Coatings, Interfaces and Films)
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14 pages, 6297 KiB  
Article
Enhancing the Elevated-Temperature Mechanical Properties of Levitation Melted NbMoTaW Refractory High-Entropy Alloys via Si Addition
by Yunzi Liu, Xiaoxiao Li, Shuaidan Lu, Jialiang Zhou, Shangkun Wu, Shengfeng Lin and Long Wang
Materials 2025, 18(15), 3465; https://doi.org/10.3390/ma18153465 - 24 Jul 2025
Abstract
To enhance the mechanical properties of NbMoTaW refractory high-entropy alloys (RHEAs), Si was added at varying concentrations (x = 0, 0.25, and 0.5) via vacuum induction levitation melting (re-melted six times for homogeneity). The microstructure and mechanical properties of NbMoTaWSix ( [...] Read more.
To enhance the mechanical properties of NbMoTaW refractory high-entropy alloys (RHEAs), Si was added at varying concentrations (x = 0, 0.25, and 0.5) via vacuum induction levitation melting (re-melted six times for homogeneity). The microstructure and mechanical properties of NbMoTaWSix (x = 0, 0.25, and 0.5) RHEAs were characterized using scanning electron microscopy (SEM), universal testing, microhardness testing, and tribological equipment. Experimental results manifested that Si addition induces the formation of the (Nb,Ta)5Si3 phase, and the volume fraction of the silicide phase increases with higher Si content, which significantly improves the alloy’s strength and hardness but deteriorates its plasticity. Enhanced wear resistance with Si addition is attributed to improved hardness and oxidation resistance. Tribological tests confirm that Si3N4 counterfaces are optimal for evaluating RHEA wear mechanisms. This work can provide guidance for the fabrication of RHEAs with excellent performance. Full article
(This article belongs to the Special Issue High-Entropy Alloys: Synthesis, Characterization, and Applications)
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19 pages, 4000 KiB  
Article
Insights of a Novel HEA Database Created from a Materials Perspective, Focusing on Wear and Corrosion Applications
by Lorena Betancor-Cazorla, Genís Clavé, Camila Barreneche and Sergi Dosta
Coatings 2025, 15(8), 865; https://doi.org/10.3390/coatings15080865 - 23 Jul 2025
Viewed by 131
Abstract
In recent years, interest in HEAs has increased exponentially due to their extraordinary properties, especially for wear- and corrosion-resistant applications. However, the main problem involves correctly selecting the HEA composition required for a specific application, as most of the data are scattered throughout [...] Read more.
In recent years, interest in HEAs has increased exponentially due to their extraordinary properties, especially for wear- and corrosion-resistant applications. However, the main problem involves correctly selecting the HEA composition required for a specific application, as most of the data are scattered throughout the literature, and only a limited number of models accurately predict the properties. Therefore, a database of 415 HEA alloys (bulk) and coatings obtained using thermal spray (TS) techniques has been created, compiled from scientific studies over the past 20 years. This tool collects information on physical, mechanical, and chemical properties, with a particular emphasis on corrosion and wear resistance. This facilitates material comparison and selection according to the needs of a specific application. In particular, the database highlights how composition and deposition technique also affect performance, identifying CoCrFeNi (CGS and in bulk) as a promising candidate for simultaneous wear and corrosion resistance. Full article
(This article belongs to the Special Issue Advances in Thermal Spray Coatings: Technologies and Applications)
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10 pages, 2135 KiB  
Article
High Strength and Fracture Resistance of Reduced-Activity W-Ta-Ti-V-Zr High-Entropy Alloy for Fusion Energy Applications
by Siva Shankar Alla, Blake Kourosh Emad and Sundeep Mukherjee
Entropy 2025, 27(8), 777; https://doi.org/10.3390/e27080777 - 23 Jul 2025
Viewed by 124
Abstract
Refractory high-entropy alloys (HEAs) are promising candidates for next-generation nuclear applications, particularly fusion reactors, due to their excellent high-temperature mechanical properties and irradiation resistance. Here, the microstructure and mechanical behavior were investigated for an equimolar WTaTiVZr HEA, designed from a palette of low-activation [...] Read more.
Refractory high-entropy alloys (HEAs) are promising candidates for next-generation nuclear applications, particularly fusion reactors, due to their excellent high-temperature mechanical properties and irradiation resistance. Here, the microstructure and mechanical behavior were investigated for an equimolar WTaTiVZr HEA, designed from a palette of low-activation elements. The as-cast alloy exhibited a dendritic microstructure composed of W-Ta rich dendrites and Zr-Ti-V rich inter-dendritic regions, both possessing a body-centered cubic (BCC) crystal structure. Room temperature bulk compression tests showed ultra-high strength of around 1.6 GPa and plastic strain ~6%, with fracture surfaces showing cleavage facets. The alloy also demonstrated excellent high-temperature strength of ~650 MPa at 500 °C. Scratch-based fracture toughness was ~38 MPa√m for the as-cast WTaTiVZr HEA compared to ~25 MPa√m for commercially used pure tungsten. This higher value of fracture toughness indicates superior damage tolerance relative to commercially used pure tungsten. These results highlight the alloy’s potential as a low-activation structural material for high-temperature plasma-facing components (PFCs) in fusion reactors. Full article
(This article belongs to the Special Issue Recent Advances in High Entropy Alloys)
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19 pages, 3800 KiB  
Article
Influence of Ni and Nb Addition in TiVCr-Based High Entropy Alloys for Room-Temperature Hydrogen Storage
by Srilakshmi Jeyaraman, Dmitri L. Danilov, Peter H. L. Notten, Udaya Bhaskar Reddy Ragula, Vaira Vignesh Ramalingam and Thirugnasambandam G. Manivasagam
Energies 2025, 18(15), 3920; https://doi.org/10.3390/en18153920 - 23 Jul 2025
Viewed by 86
Abstract
TiVCr-based alloys are well-explored body-centered cubic (BCC) materials for hydrogen storage applications that can potentially store higher amounts of hydrogen at moderate temperatures. The challenge remains in optimizing the alloy-hydrogen stability, and several transition elements have been found to support the reduction in [...] Read more.
TiVCr-based alloys are well-explored body-centered cubic (BCC) materials for hydrogen storage applications that can potentially store higher amounts of hydrogen at moderate temperatures. The challenge remains in optimizing the alloy-hydrogen stability, and several transition elements have been found to support the reduction in the hydride stability. In this study, Ni and Nb transition elements were incorporated into the TiVCr alloy system to thoroughly understand their influence on the (de)hydrogenation kinetics and thermodynamic properties. Three different compositions, (TiVCr)95Ni5, (TiVCr)90 Ni10, and (TiVCr)95Ni5Nb5, were prepared via arc melting. The as-prepared samples showed the formation of a dual-phase BCC solid solution and secondary phase precipitates. The samples were characterized using hydrogen sorption studies. Among the studied compositions, (TiVCr)90Ni10 exhibited the highest hydrogen absorption capacity of 3 wt%, whereas both (TiVCr)95Ni5 and (TiVCr)90Ni5Nb5 absorbed up to 2.5 wt% hydrogen. The kinetics of (de)hydrogenation were modeled using the JMAK and 3D Jander diffusion models. The kinetics results showed that the presence of Ni improved hydrogen adsorption at the interface level, whereas Nb substitution enhanced diffusion and hydrogen release at room temperature. Thus, the addition of Ni and Nb to Ti-V-Cr-based high-entropy alloys significantly improved the hydrogen absorption and desorption properties at room temperature for gas-phase hydrogen storage. Full article
(This article belongs to the Special Issue Hydrogen Energy Storage: Materials, Methods and Perspectives)
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25 pages, 3515 KiB  
Article
Optimizing Sustainable Machining Conditions for Incoloy 800HT Using Twin-Nozzle MQL with Bio-Based Groundnut Oil Lubrication
by Ramai Ranjan Panigrahi, Ramanuj Kumar, Ashok Kumar Sahoo and Amlana Panda
Lubricants 2025, 13(8), 320; https://doi.org/10.3390/lubricants13080320 - 23 Jul 2025
Viewed by 170
Abstract
This study explores the machinability of Incoloy 800HT (high temperature) under a sustainable lubrication approach, employing a twin-nozzle minimum quantity lubrication (MQL) system with groundnut oil as a green cutting fluid. The evaluation focuses on key performance indicators, including surface roughness, tool flank [...] Read more.
This study explores the machinability of Incoloy 800HT (high temperature) under a sustainable lubrication approach, employing a twin-nozzle minimum quantity lubrication (MQL) system with groundnut oil as a green cutting fluid. The evaluation focuses on key performance indicators, including surface roughness, tool flank wear, power consumption, carbon emissions, and chip morphology. Groundnut oil, a biodegradable and nontoxic lubricant, was chosen to enhance environmental compatibility while maintaining effective cutting performance. The Taguchi L16 orthogonal array (three factors and four levels) was utilized to conduct experimental trials to analyze machining characteristics. The best surface quality (surface roughness, Ra = 0.514 µm) was obtained at the lowest depth of cut (0.2 mm), modest feed (0.1 mm/rev), and moderate cutting speed (160 m/min). The higher ranges of flank wear are found under higher cutting speed conditions (320 and 240 m/min), while lower wear values (<0.09 mm) were observed under lower speed conditions (80 and 160 m/min). An entropy-integrated multi-response optimization using the MOORA (multi-objective optimization based on ratio analysis) method was employed to identify optimal machining parameters, considering the trade-offs among multiple conflicting objectives. The entropy method was used to assign weights to each response. The obtained optimal conditions are as follows: cutting speed = 160 m/min, feed = 0.1 mm/rev, and depth of cut = 0.2 mm. Optimized outcomes suggest that this green machining strategy offers a viable alternative for sustainable manufacturing of difficult-to-machine alloys like Incoloy 800 HT. Full article
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24 pages, 5129 KiB  
Article
On the Solidification and Phase Stability of Re-Bearing High-Entropy Superalloys with Hierarchical Microstructures
by Wei-Che Hsu, Takuma Saito, Mainak Saha, Hideyuki Murakami, Taisuke Sasaki and An-Chou Yeh
Metals 2025, 15(8), 820; https://doi.org/10.3390/met15080820 - 22 Jul 2025
Viewed by 221
Abstract
This study presents the design and microstructural investigation of a single-crystal (SX) Re-bearing high-entropy superalloy (HESA-X1) featuring a thermally stable γ–γ′–γ hierarchical microstructure. The alloy exhibits FCC γ nanoparticles embedded within L12-ordered γ′ precipitates, themselves distributed in a γ matrix, with [...] Read more.
This study presents the design and microstructural investigation of a single-crystal (SX) Re-bearing high-entropy superalloy (HESA-X1) featuring a thermally stable γ–γ′–γ hierarchical microstructure. The alloy exhibits FCC γ nanoparticles embedded within L12-ordered γ′ precipitates, themselves distributed in a γ matrix, with the suppression of detrimental topologically close-packed (TCP) phases. To elucidate solidification behavior and phase stability, Scheil–Gulliver and TC-PRISMA simulations were conducted alongside SEM and XRD analyses. Near-atomic scale analysis in 3D using Atom Probe Tomography (APT) revealed pronounced elemental partitioning, with Re strongly segregating to the γ matrix, while Al and Ti were preferentially enriched in the γ′ phase. Notably, Re demonstrated a unique partitioning behavior compared to conventional superalloys, facilitating the formation and stabilization of γ nanoparticles during two-step aging (Ag-2). These γ nanoparticles significantly contribute to improved mechanical properties. Long-term aging (up to 200 h) at 750–850 °C confirmed exceptional phase stability, with minimal coarsening of γ′ and retention of γ nanoparticles. The coarsening rate constant K of γ′ at 750 °C was significantly lower than that of Re-free HESA, confirming the diffusion-suppressing effect of Re. These findings highlight critical roles of Re in enhancing microstructural stability by reducing atomic mobility, enabling the development of next-generation HESAs with superior thermal and mechanical properties for high-temperature applications. Full article
(This article belongs to the Special Issue Solidification and Casting of Metals and Alloys (2nd Edition))
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17 pages, 12649 KiB  
Article
Microstructure, Mechanical Properties, and Electrochemical Corrosion Behavior of CoCrFeNiNb and CoCrFeNiV High-Entropy Alloys Prepared via Mechanical Alloying and Spark Plasma Sintering
by Yan Zhu, Yiwen Liu, Zhaocang Meng and Jianke Tian
Metals 2025, 15(7), 814; https://doi.org/10.3390/met15070814 - 21 Jul 2025
Viewed by 150
Abstract
This study investigates the microstructural evolution, mechanical behavior, and electrochemical performance of CoCrFeNiNb and CoCrFeNiV HEAs fabricated via mechanical alloying and spark plasma sintering. Microstructural analyses reveal that the alloys have a face-centered cubic (FCC) matrix with Nb-enriched Laves and V-enriched σ phases. [...] Read more.
This study investigates the microstructural evolution, mechanical behavior, and electrochemical performance of CoCrFeNiNb and CoCrFeNiV HEAs fabricated via mechanical alloying and spark plasma sintering. Microstructural analyses reveal that the alloys have a face-centered cubic (FCC) matrix with Nb-enriched Laves and V-enriched σ phases. The CoCrFeNiNb HEA exhibits superior compressive strength and hardness than CoCrFeNiV due to uniform Laves phases distribution. Fracture surface analysis reveals that at lower sintering temperatures, the fracture is primarily caused by incomplete particle bonding, whereas at higher temperatures, brittle fracture modes dominated via transgranular cracking become predominant. The research results of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) show that both alloys exhibited superior electrochemical stability in a 3.5 wt.% NaCl solution compared to the CoCrFeNi base alloy. X-ray photoelectron spectroscopy (XPS) analysis confirms the formation of stable oxide layers (Nb2O5 and V2O3) on the precipitated phases, acting as protective barriers against chloride ion penetration. The selective oxidation of Nb and V improves the integrity of the passive film, reducing the corrosion rates and enhancing the long-term durability. These findings highlight the critical role of precipitated phases in enhancing the corrosion resistance of HEAs, and emphasize their potential for use in extreme environments. Full article
(This article belongs to the Special Issue High-Entropy Alloys: Processing and Properties)
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23 pages, 1314 KiB  
Review
Electrochemical and Electroless Deposition of High-Entropy Alloy Thin Films: A Review of Plating Conditions, Properties, and Applications
by Ewa Rudnik
Appl. Sci. 2025, 15(14), 8009; https://doi.org/10.3390/app15148009 - 18 Jul 2025
Viewed by 193
Abstract
High-entropy alloys (HEAs) represent a breakthrough class of materials characterized by a unique combination of properties derived from their multielement compositions. This review explores the current advancements in both electrochemical and electroless deposition techniques for synthesizing HEA thin films. This paper discusses the [...] Read more.
High-entropy alloys (HEAs) represent a breakthrough class of materials characterized by a unique combination of properties derived from their multielement compositions. This review explores the current advancements in both electrochemical and electroless deposition techniques for synthesizing HEA thin films. This paper discusses the crucial plating conditions using aqueous or organic electrolytes and various current/potential modes that influence the formation, quality, and properties of these complex alloy coatings. Particular attention is given to their emerging applications in areas such as catalysis, protective coatings, microelectronics, and liquids’ separation. A comparison of electrochemical versus electroless methods reveals insights into the advantages and limitations of each technique for research and industrial use. This comprehensive review aims to guide further innovation in the development and application of HEA coatings. Full article
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14 pages, 10913 KiB  
Article
Lattice Distortion Effects on Mechanical Properties in Nb-Ti-V-Zr Refractory Medium-Entropy Alloys
by Xiaochang Xie, Ping Yang, Yuefei Jia and Yandong Jia
Materials 2025, 18(14), 3356; https://doi.org/10.3390/ma18143356 - 17 Jul 2025
Viewed by 180
Abstract
Medium-entropy alloys (MEAs) have attracted significant attention due to their unique structure–property relationships. In this study, we examine the effects of lattice distortion on the mechanical properties of Nb-Ti-V-Zr MEAs, focusing on two alloy series: Nb(Ti1.5V)xZr and Nb(TiV)x [...] Read more.
Medium-entropy alloys (MEAs) have attracted significant attention due to their unique structure–property relationships. In this study, we examine the effects of lattice distortion on the mechanical properties of Nb-Ti-V-Zr MEAs, focusing on two alloy series: Nb(Ti1.5V)xZr and Nb(TiV)xZr (x = 1, 2, 3, 4 and 5). Experimental results show that the Nb(TiV)xZr r alloys exhibit greater atomic size mismatches and increased lattice distortion compared to the Nb(Ti1.5V)xZr alloys, leading to higher yield strengths via enhanced solid-solution strengthening. However, excessive lattice distortion does not ensure an optimal strength–ductility balance, as the alloys with the highest distortion demonstrate limited plasticity. Thus, moderate reduction in lattice distortion proves beneficial in achieving an excellent compromise between strength and ductility. These findings offer valuable guidance for leveraging lattice distortion in the design of high-strength, high-ductility, body-centered cubic (BCC) MEAs for extreme environments. Full article
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21 pages, 7349 KiB  
Article
Effect of Ti Doping of Al0.7CoCrFeNi-Based High Entropy Alloys on Their Erosion Resistance by Solid Particles
by Wojciech J. Nowak, Tadeusz Kubaszek, Andrzej Gradzik, Małgorzata Grądzka-Dahlke, Dariusz Perkowski, Marzena Tokarewicz, Mariusz Walczak and Mirosław Szala
Materials 2025, 18(14), 3328; https://doi.org/10.3390/ma18143328 - 15 Jul 2025
Viewed by 210
Abstract
The erosion resistance of materials against solid particles is a very important property, especially in the transportation of powders or in aeronautics (dust inside jet engines). There is a strong need to introduce new materials that have higher solid particle erosion resistance than [...] Read more.
The erosion resistance of materials against solid particles is a very important property, especially in the transportation of powders or in aeronautics (dust inside jet engines). There is a strong need to introduce new materials that have higher solid particle erosion resistance than state-of-the-art materials. Thus, in the present work, the solid erosion particles of high entropy alloys (HEAs) based on the Al0.7CoCrFeNi matrix were studied compared to the state-of-the-art stainless steel AISI 304. Furthermore, the effect of the addition of Ti to HEAs on hardness and erosion resistance was investigated. Current research included the development of the chemical composition of a new kind of HEA designed on the basis of thermodynamical calculations performed in CALPHAD, its manufacturing, full characterization involving microstructural and phase analyses, hardness measurements, solid particle erosion tests, and finally, the elucidation of erosion mechanisms. It was found that HEAs showed higher hardness as well as erosion resistance than AISI 304. Moreover, it was found that the increase in Ti content in an HEA resulted in an increase in the hardness and resistance to the erosion of the studied HEA. As the main reason for this phenomenon, the stabilization of the β-BCC phase, suppression of the α-FCC phase, and the appearance of the Ni3Ti phase in the studied HEA were claimed. Full article
(This article belongs to the Special Issue New Advances in High Entropy Alloys)
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13 pages, 5099 KiB  
Article
Effect of Grain Size Distribution on Frictional Wear and Corrosion Properties of (FeCoNi)86Al7Ti7 High-Entropy Alloys
by Qinhu Sun, Pan Ma, Hong Yang, Kaiqiang Xie, Shiguang Wan, Chunqi Sheng, Zhibo Chen, Hongji Yang, Yandong Jia and Konda Gokuldoss Prashanth
Entropy 2025, 27(7), 747; https://doi.org/10.3390/e27070747 - 12 Jul 2025
Viewed by 183
Abstract
Optimization of grain size distribution in high-entropy alloys (HEAs) is a promising design strategy to overcome wear and corrosion resistance. In this study, a (FeCoNi)86Al7Ti7 high-entropy alloy with customized isometric and heterogeneous structure, as well as fine-crystal isometric [...] Read more.
Optimization of grain size distribution in high-entropy alloys (HEAs) is a promising design strategy to overcome wear and corrosion resistance. In this study, a (FeCoNi)86Al7Ti7 high-entropy alloy with customized isometric and heterogeneous structure, as well as fine-crystal isometric design by SPS, is investigated for microstructure, surface morphology, hardness, frictional wear, and corrosion resistance. The effects of the SPS process on the microstructure and mechanical behavior are elucidated, and the frictional wear and corrosion resistance of the alloys are improved with heterogeneous structural fine-grain strengthening and uniform fine-grain strengthening. The wear mechanisms and corrosion behavior mechanisms of (FeCoNi)86Al7Ti7 HEAs with different phase structure designs are elaborated. This work highlights the potential of using powder metallurgy to efficiently and precisely control and optimize the multi-scale microstructure of high-entropy alloys, thereby improving their frictional wear and corrosion properties in demanding applications. Full article
(This article belongs to the Special Issue Recent Advances in High Entropy Alloys)
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14 pages, 6398 KiB  
Article
Corrosion Behavior of Additively Manufactured GRX-810 Alloy in 3.5 wt.% NaCl
by Peter Omoniyi, Samuel Alfred, Kenneth Looby, Olu Bamiduro, Mehdi Amiri and Gbadebo Owolabi
Materials 2025, 18(14), 3252; https://doi.org/10.3390/ma18143252 - 10 Jul 2025
Viewed by 267
Abstract
This study examines the corrosion characteristics of GRX-810, a NiCoCr-based high entropy alloy, in a simulated marine environment represented by 3.5 wt.% NaCl solution. The research employs electrochemical and surface analysis techniques to evaluate the corrosion performance and protective mechanisms of this alloy. [...] Read more.
This study examines the corrosion characteristics of GRX-810, a NiCoCr-based high entropy alloy, in a simulated marine environment represented by 3.5 wt.% NaCl solution. The research employs electrochemical and surface analysis techniques to evaluate the corrosion performance and protective mechanisms of this alloy. Electrochemical characterization was performed using potentiodynamic polarization to determine critical corrosion parameters, including corrosion potential and current density, along with electrochemical impedance spectroscopy to assess the stability and protective qualities of the oxide film. Surface analytical techniques provided detailed microstructural and compositional insights, with scanning electron microscopy revealing the morphology of corrosion products, energy-dispersive X-ray spectroscopy identifying elemental distribution in the passive layer, and X-ray diffraction confirming the chemical composition and crystalline structure of surface oxide. The results demonstrated distinct corrosion resistance behavior between the different processing conditions of the alloy. The laser powder bed fused (LPBF) specimens in the as-built condition exhibited superior corrosion resistance compared to their hot isostatically pressed (HIPed) counterparts, as evidenced by higher corrosion potentials and lower current densities. Microscopic examination revealed the formation of a dense, continuous layer of corrosion products on the alloy surface, indicating effective barrier protection against chloride ion penetration. A compositional analysis of all samples identified oxide film enriched with chromium, nickel, cobalt, aluminum, titanium, and silicon. XRD characterization confirmed the presence of chromium oxide (Cr2O3) as the primary protective phase, with additional oxides contributing to the stability of the film. This oxide mixture demonstrated the alloy’s ability to maintain passivity and effective repassivation following film breakdown. Full article
(This article belongs to the Special Issue Study on Electrochemical Behavior and Corrosion of Materials)
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15 pages, 4232 KiB  
Article
The Growth Kinetic and Ultra High Hardness of CoCrFeNiTi High–Entropy Alloy by Mechanical Alloying and Spark Plasma Sintering
by Tiejun Qu, Mingpu Liu, Chuanhua Yang, Xin Wang and Junfa Wang
Materials 2025, 18(14), 3242; https://doi.org/10.3390/ma18143242 - 9 Jul 2025
Viewed by 312
Abstract
In this paper, the impact of mechanical alloying (MA) and spark plasma sintering (SPS) on the phase evolution and mechanical properties development of CoCrFeNiTi high–entropy alloys (HEAs) was investigated. The microstructure and properties of the material were examined, using X-ray diffraction (XRD) for [...] Read more.
In this paper, the impact of mechanical alloying (MA) and spark plasma sintering (SPS) on the phase evolution and mechanical properties development of CoCrFeNiTi high–entropy alloys (HEAs) was investigated. The microstructure and properties of the material were examined, using X-ray diffraction (XRD) for phase identification, scanning electron microscopy (SEM) for surface morphology observation, transmission electron microscopy (TEM) for microstructural analysis, and hardness testing to evaluate mechanical performance. The milled powder exhibited nanocrystalline solid solution microstructure with grain sizes below 48 nm, composed of 83% face–centered cubic (FCC) and 17% body–centered cubic (BCC) phases. Mechanically, the bulk CoCrFeNiTi alloy exhibited exceptional strength attributes, as evidenced by a Vickers hardness value reaching 675 Hv, along with a compressive strength of 1894 MPa and a yield stress of 1238 MPa. These findings suggested that the synergistic effects of mechanical alloying and SPS processing can precisely control the phase stability, microstructure refinement, and property optimization in CoCrFeNiTi HEA, with particular promise for advanced structural applications. Full article
(This article belongs to the Special Issue Advances in Plasma and Laser Engineering (Second Edition))
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18 pages, 2433 KiB  
Article
Thermodynamic Assessment of the Pyrometallurgical Recovery of a Pb-Ag Alloy from a Mixture of Ammonium Jarosite–Lead Paste Wastes
by Jose Enrique Sanchez Vite, Alejandro Cruz Ramírez, Manuel Eduardo Flores Favela, Ricardo Gerardo Sánchez Alvarado, José Antonio Romero Serrano, Margarita García Hernández, Teresita del Refugio Jiménez Romero and Juan Cancio Jiménez Lugos
Recycling 2025, 10(4), 136; https://doi.org/10.3390/recycling10040136 - 8 Jul 2025
Viewed by 383
Abstract
A previously pyrometallurgical process, developed to obtain a Pb-Ag alloy and a slag rich in sulfur from the recycling of a mixture of industrial wastes of jarosite and lead paste, was thermodynamically assessed at 1200 °C. The industrial jarosite sourced from a Mexican [...] Read more.
A previously pyrometallurgical process, developed to obtain a Pb-Ag alloy and a slag rich in sulfur from the recycling of a mixture of industrial wastes of jarosite and lead paste, was thermodynamically assessed at 1200 °C. The industrial jarosite sourced from a Mexican zinc hydrometallurgical plant corresponded to an ammonium jarosite with a measurable silver content. The specific heat capacity (Cp) of the ammonium jarosite was obtained from TGA and DSC measurements, as well as the thermodynamic functions of enthalpy, entropy, and Gibbs free energy. The Cp was successfully modeled using polynomial regression, with a second-degree polynomial employed to describe the low-temperature behavior. The thermodynamic data generated were input into the thermodynamic software FactSage 8.2 for modeling of the lead paste–ammonium jarosite-Na2CO3-SiC system and represented by stability phase diagrams. The thermodynamic assessment of the pyrometallurgical process predicted compounds formed at high temperatures, showing that a Pb-Ag alloy and a slag rich in Na, S, and Fe (NaFeS2 and NaFeO2) were obtained. The compounds formed evidence of the effective sulfur retention in the slag, which is crucial for mitigating SO2 emissions during high-temperature treatments. The experimental compounds, after solidification, were determined by X-ray diffraction measurements to be Na2Fe(SO4)2 and Na2(SO4), which reasonably match the thermodynamic assessment. The heat capacity of the ammonium jarosite provides essential thermodynamic insights into the compositional complexities of industrial waste, which are particularly relevant for thermodynamic modeling and process optimization in pyrometallurgical systems aimed at metal recovery and residue valorization. Full article
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