Search Results (977)

Nickel-based superalloy components prepared by laser powder bed fusion (LPBF) are increasingly being used in the hot ends of aeroengines, which still need to be laser-welded to realize the assembly connection of large closed structures. However, the unique microstructural characteristics of LPBFed parts render them more poorly weldable than casts and wroughts, especially in cracking-sensitive superalloys. In this study, cracking mechanisms were analyzed by performing laser deep fusion welding on an LPBFed Haynes 230 alloy. The key factors leading to weld cracking were strongly correlated with the low-melting-point TCP phases enriched with W, Si, Al, and silicides, both of which tended to be distributed in the boron(B)-rich region and exhibited poor coherence with the matrix. In addition, the flow behavior of the molten pool affected the solidification rate of the weld, resulting in large solidification shrinkage stresses in the cracking-sensitive zone (CZ) part of the weld. In order to minimize the development conditions of the cracking-sensitive phases, reducing the content of W (from 14.96 to 13.56 wt.%) and Si (from 0.47 to 0.25 wt.%) was chosen to alleviate the segregation of W, Si and C elements in the solid phase at the end of solidification. Thus, TCP phase and silicides were transformed into carbides, which successfully suppressed weld cracking, reducing the crack depth ratio from 0.70 ± 0.08 to zero. New insights into the weldability improvement and crack inhibition mechanism of laser-welded additively manufactured cracking-sensitive superalloys are provided, accelerating the rapid application of large assemblies. Full article

Aluminum alloy capsules play a critical role in shape control, heat transfer, and pressure transmission during the PM-HIP sintering of Al-based powders. As the weakest part of the capsule, the reliability of the welded joint is crucial for the safe operation of the HIP process and the quality of the final product. This study investigated the effects of two typical HIP temperatures on the evolution of second phases and texture. The results show that: (1) At 400 °C, suppressed Si diffusion retains a continuous, low-melting-point Al-Si eutectic network and needle-like secondary phases in the weld zone, thereby impeding residual stress relief. Compositional segregation in the heat-affected zone weakens grain boundary stability. The texture undergoes only limited recovery, with a strong <100> orientation retained and micro-strain not effectively relieved, restricting joint ductility. (2) At 510 °C, Si is sufficiently spheroidized, forming a bead-like structure. Needle-like second phases transform into globular/short-rod morphologies, disrupting the continuity of the brittle phases. Simultaneously, complete recrystallization is induced, resulting in a randomized texture and significant release of micro-strain, thereby improving microstructural homogeneity and plastic deformation capacity. This study suggests that the internal stress concentration arising from the low-melting-point eutectic phase and strong texture poses a failure risk for the capsule. Therefore, employing the 510 °C HIP process to achieve second-phase spheroidization and texture weakening can significantly mitigate this failure risk. Full article

High-entropy alloys (HEAs) offer attractive combinations of mechanical performance, thermal stability, and compositional flexibility, making them promising candidates for advanced structural applications. Laser-based additive manufacturing, particularly laser powder bed fusion (LPBF) and laser-directed energy deposition (LDED), enables the fabrication of geometrically complex HEA components with non-equilibrium microstructures. However, the distinct thermal histories of LPBF and LDED, with typical cooling rates of approximately 10⁵–10⁷ K s⁻¹ and 10²–10⁴ K s⁻¹, respectively, strongly govern solidification behavior, elemental segregation, residual stress development, defect formation, and mechanical properties. Although previous reviews have discussed additively manufactured HEAs, an integrated framework linking composition design, printability, LPBF/LDED processing, microstructural evolution, post-processing, and industrial qualification remains limited. Therefore, this review establishes a unified composition–process–structure–property framework for laser additively manufactured HEAs. Fundamental HEA concepts, LPBF/LDED process characteristics, solidification behavior, phase formation, defect evolution, and mechanical performance from ambient to elevated temperatures are systematically discussed across representative FCC, refractory, and dual-phase HEA systems. This review emphasizes that printability should be considered during alloy design by correlating composition-dependent solidification characteristics, cracking susceptibility, phase stability, and defect formation with mechanical performance. Post-processing treatments are shown to modify residual stress, microsegregation, precipitation behavior, porosity, and deformation mechanisms, although their benefits must be balanced against thermal softening or brittle phase formation. Finally, CALPHAD, integrated computational materials engineering (ICME), machine learning (ML), and in situ monitoring are identified as promising tools for accelerating alloy and process optimization, while reproducible process windows, defect-control criteria, databases, and qualification protocols remain essential for industrial implementation. Full article

This study investigates the effects of phosphorus (P) on the phases developed during sintering and their impact on the stability of key phases in iron ore sinter, particularly the silico-ferrite of calcium and aluminum (‘SFCA’) series of phases. Two complementary systems were studied: an industrially representative blend of natural iron ores (JSM) and a synthetic high-purity SFCA analogue (SA) system designed to promote controlled SFCA formation. Phosphorus was added as hydroxyapatite (HA) at levels of 0.5, 1.0, 1.5 and 5 wt.%. To simulate a standard sintering profile, experiments were conducted over a range of temperatures for 3 min in a controlled low-oxygen-potential atmosphere of pO₂ = 5 × 10⁻³ atm. A modified Bond Abrasion test was used to evaluate the tumble index (TI) strength of the samples, and the chemistry, mineralogy and microstructure of all sintered products were analyzed. Results indicated that all P-doped JSM samples fired within the temperature range of 1300 to 1330 °C met the minimum strength requirement (TI = 80%) for producing high-quality sinters. Adding small to medium amounts of HA (≤1.5 wt.%) to both compositions had a limited impact on the overall mineral phases. Conversely, adding a high amount of HA (5 wt.%) encouraged the creation of Ca–Si–P phases. Analysis of the microstructure, minerals, and microchemistry indicated that P tended to segregate phases rich in phosphorus by interacting with calcium oxide and silica. The findings from the study highlight that at the low levels of P typically found in iron ores, there is no significant impact on the strength, mineralogy and phases formed during sintering. Full article

During long-term service, asphalt pavements undergo environmental stress and ageing, which cause cracking, rutting, and other distresses and raise maintenance costs. Polyurethane (PU) has high mechanical strength, elastic recovery, and ageing resistance due to its unique molecular structure. As an asphalt modifier, PU has been reported to improve high-temperature stability, moisture resistance, and durability. However, PU and asphalt differ greatly in polarity, density, viscosity, and phase structure, and these differences often lead to segregation and phase separation. The prepolymer method can mitigate these compatibility limitations by adjusting molecular weight, terminal-group activity, and soft/hard segment ratio before dispersion, chain extension, crosslinking, and post-curing in asphalt, resulting in better compatibility and more controllable processing. This review discusses PU soft/hard segment structures, asphalt composition, prepolymer synthesis and curing, microstructural evolution, pavement performance, storage stability, and use in other systems to clarify modification mechanisms and potential applications. This critical review aims to clarify material–reaction–process–performance relationships within the prepolymer route, with scope limited to molecular design, preparation mechanisms, performance, storage stability, and representative engineering applications. Future work should consider real service conditions and build multiscale evaluation frameworks that jointly optimise prepolymer design, processing, storage stability, and pavement performance, helping translate laboratory findings into low-carbon, long-life road materials that can be produced at scale. Full article

A novel (TaWZrHf)₉₅Y₅ refractory high-entropy alloy (RHEA) matrix was fabricated via vacuum hot pressing (VHP) sintering and subsequently modified through laser remelting (LR) surface treatment. Thermodynamic phase diagram calculations predicted the alloy’s dual-phase BCC structure, and the effects of LR on phase composition, microstructure, and mechanical properties were systematically investigated. LR induced a significant phase transition, promoting rapid solidification and substantial grain refinement. The surface hardness increased to 848 HV₀.₂, approximately 1.5 times higher than that of the matrix, while the compressive strength reached 1635 MPa, surpassing the matrix by 200 MPa without compromising ductility. Importantly, the LR process effectively mitigated rare-earth (yttrium) segregation and loss, a common challenge in conventional arc melting of refractory HEAs, thereby enhancing solid solution strengthening and phase stability. This work pioneers the application of laser surface engineering to VHP-sintered refractory HEAs, bridging critical gaps in fabrication, microstructural optimization, and performance enhancement, and offering valuable insights for the future design of high-performance multi-principal element alloy development. Full article

Performance and durability of solid oxide cells are ruled by surface and interface phenomena occurring under operation. Electrode elementary reactions involve adsorption, charge transfer, surface diffusion and incorporation processes that are sensitive to the applied operating conditions and defect concentration. However, key degradation mechanisms such as cation segregation, catalyst deactivation, phase transformations and microstructural evolution originate at/near the electrode surface. Consequently, understanding the surface chemistry of electrode materials is essential for the development of the next generation electrodes. In this frame, Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) has emerged as a powerful tool to probe chemically active surfaces under more realistic environments, thus correlating surface science and electrochemistry. This review covers the principles of NAP-XPS and its application to solid oxide cell materials, including ceria-based model electrodes, Ni-containing fuel electrodes, exsolved perovskites and mixed ionic-electronic conducting air electrodes. NAP-XPS demonstrated the ability to directly monitor the dynamic state of the electrode surface under controlled operating conditions. Common mechanistic insights and emerging trends are highlighted, together with potential limitations associated with current experimental configurations. Overall, combined NAP-XPS and electrochemical analyses appear to hold the potential for linking surface chemistry with electrode performance and degradation, thus supporting the rational design of the next-generation solid oxide cell materials. Full article

This study systematically investigates the effects of varying Ni doping levels (1.0–7.0 wt.%) on the microstructure, static magnetic properties, and high-frequency dynamic magnetic performance of Fe-5.5 wt.% Si soft magnetic composites (SMCs). Toroidal core samples were fabricated using powder metallurgy combined with silicone resin coating and high-temperature annealing. The influence of Ni doping on phase composition, morphology, saturation magnetization, coercivity, effective permeability, quality factor, total core loss and its components, and DC bias characteristics was comprehensively evaluated by XRD, SEM, EDS, hysteresis loop testing, and DC bias measurements. The results indicate that an appropriate Ni content (3.0–5.0 wt.%) promotes the formation of α-Fe(Si,Ni) solid solution and (Fe,Ni)₃Si ordered phases, optimizes grain size and structural ordering, enhances saturation magnetization, and reduces coercivity. In contrast, excessive Ni doping (7.0 wt.%) leads to Ni segregation at grain boundaries, forming strong pinning centers that significantly increase coercivity and hysteresis loss. Within the wide frequency range of 1–100 kHz, Ni doping improves the permeability retention under DC bias but reduces the initial effective permeability. Notably, the sample with 5.0 wt.% Ni exhibits the highest quality factor (Q value) across the entire frequency range, demonstrating the best overall performance. This study provides experimental evidence and theoretical guidance for developing high-saturation-resistance, low-loss soft magnetic composites for medium-to-high-frequency applications. Full article

Background: Congenital ichthyoses are a clinically and genetically heterogeneous group of Mendelian disorders of cornification. According to the 2025 classification, non-syndromic epidermal differentiation disorders (nEDDs) are categorized based on the biological function of the causative gene products. Variants in TGM1 cause a transglutaminase-related nEDD (TGM1-nEDD), typically corresponding to the traditional phenotype of lamellar ichthyosis (LI), whereas biallelic variants in CYP4F22 cause a lipid-metabolism-related nEDD (CYP4F22-nEDD), formerly classified as ARCI type 5. The latter form is characterized by impaired acylceramide synthesis and epidermal barrier dysfunction. Although CYP4F22-nEDD usually follows a persistent course, considerable phenotypic variability has been reported, including milder forms and self-improving collodion ichthyosis. Methods and Results: We report two unrelated Italian neonates with congenital ichthyosis, investigated by targeted next-generation sequencing (NGS). Patient 1 presented with a phenotype consistent with LI and carried compound heterozygous TGM1 variants: the known pathogenic c.1147G>A p.(Val383Met) variant, and the novel c.860C>T p.(Thr287Ile) variant, classified as likely pathogenic according to the American College of Medical Genetics and Genomics (ACMG) criteria. Patient 2 presented as a collodion baby and carried two heterozygous CYP4F22 variants: the known pathogenic nonsense variant c.1084C>T p.(Arg362Ter), and the previously unreported in-frame deletion c.543_545del p.(Ile181del), currently classified as a variant of uncertain significance (VUS). Because parental segregation analysis was unavailable, the allelic phase of the CYP4F22 variants could not be established, and molecular confirmation of autosomal recessive inheritance was not possible. Both patients showed marked clinical improvement during follow-up with topical emollient therapy alone. In Patient 2, the clinical course was consistent with a self-improving collodion ichthyosis phenotype. A structured literature review was performed to contextualize the clinical and molecular findings. Conclusions: These cases illustrate the clinical and genetic heterogeneity of nEDDs, and confirm the value of NGS in the management of neonates with congenital ichthyosis. The principal novelty of this report lies in the identification of previously unreported TGM1 and CYP4F22 sequence variants. While functional validation is lacking, integration of clinical and genetic findings with literature evidence may assist interpretation of rare variants and support genetic counselling. Full article

Aerospace die forgings are safety-critical structural products whose service performance is governed by coupled microstructural evolution across multiple length scales rather than by any single descriptor. This review critically synthesizes recent progress in multiscale characterization and process–structure–property analysis of aerospace die forgings, with emphasis on forged titanium alloys, wrought nickel-based superalloys, and high-strength aluminum alloys. A practical framework is first established by linking macroscale metal-flow integrity and defect control with mesoscale gradients, microscale grain-boundary and texture evolution, and nanoscale precipitation, segregation, and interface states. The principal characterization routes are then discussed, including X-ray diffraction, EBSD/3D-EBSD, TEM/STEM, atom probe tomography, tomography-based defect evaluation, and correlative workflows. The alloy-specific sections are organized around mechanisms and property consequences rather than isolated micrographs. Finally, the review discusses how multiscale descriptors can support crystal-plasticity, phase-field, cellular-automata, and ICME-oriented modeling, and identifies future priorities in three-dimensional characterization, quantitative descriptor extraction, uncertainty-aware modeling, environmental degradation assessment, and closed-loop process optimization. Overall, the performance of aerospace die forgings is shown to depend on coordinated control of phase stability, grain-boundary network evolution, precipitation state, defect population, and location-dependent heterogeneity across the full manufacturing route. Full article

This study investigates the nanomechanical response of aluminum substrates coated with crystalline or amorphous equiatomic FeNiCrCo compositionally complex alloy (CCA) layers using molecular dynamics nanoindentation. We evaluated the influence of coating microstructure and pre-relaxation via Monte Carlo/molecular dynamics (MC/MD) on deformation behavior at shallow (35 Å) and deep (65 Å) indentation depths. The relaxation process is critical for equilibrating internal stresses and homogenizing the initial stress field in amorphous phases, while preventing chaotic defect multiplication in crystalline lattices, yet it simultaneously promotes Fe and Cr surface segregation consistent with the equilibrium chemical short-range ordering of the alloy. The results reveal distinct deformation mechanisms: crystalline coatings exhibit higher peak indentation forces of about 300 ± 16 eV/Å characterized by discrete force fluctuations indicative of localized plastic events, while amorphous coatings show lower peak loads (~170–220 ± 12 eV/Å), corresponding to a reduction in load-bearing capacity of roughly 25%–40%, and smooth, continuous deformation governed by shear transformation zones. Notably, in amorphous systems, pressure-induced local crystallization occurs under load, with ordered FCC/HCP regions persisting after unloading, indicating partial irreversibility of the phase transition. Upon deep indentation into the substrate, the amorphous system exhibits a sharp increase in stiffness due to substrate compaction, whereas the crystalline system maintains high load-bearing capacity with reduced defect density in the relaxed state compared to the non-relaxed counterpart. Relaxation significantly reduces force-curve fluctuations in both systems, enhancing the stability of the mechanical response. Compared with uncoated aluminum, which exhibits extensive twin propagation and deep defect penetration, the FeNiCrCo-coated systems approximately halve the defect penetration depth and reduce the defective-atom volume fraction in the substrate by about a factor of two, thereby more effectively confining plastic deformation and preserving substrate integrity under the simulated conditions. These findings demonstrate that the synergy between coating crystallinity and rigorous relaxation protocols governs stress distribution patterns—localized hotspots in amorphous phases versus extended networks in crystalline ones—providing key insights for designing advanced protective coating–substrate systems with optimized mechanical performance. Full article

Fe-Cr-C-based coatings were fabricated on Q690 steel via ultrasonic vibration-assisted plasma cladding at varying ultrasonic powers (0–65 W) with a fixed frequency of 18.5 kHz. The coatings primarily consisted of martensite, retained austenite, and (Cr,Fe)₇C₃ carbides, along with (Cr,Fe,Mo)-B borides along grain boundaries. Increasing ultrasonic power promoted cavitation and acoustic streaming, which refined columnar dendrites, reduced elemental segregation (notably for B and Mo), and increased the fraction of fine equiaxed grains without altering phase composition. As a result, the average microhardness increased from 797.1 to 828.5 HV0.1. The friction coefficient decreased from 0.675 to 0.626, while the wear-track width, wear depth, and wear mass loss decreased from 4.0 mm to 2.5 mm, from 112.5 μm to 32.4 μm, and from 20.40 mg to 4.75 mg, respectively. The wear mechanism shifted from severe adhesive wear to mild abrasive wear. These results demonstrate that increasing ultrasonic vibration power effectively refines the solidification microstructure and significantly improves the hardness and wear resistance of plasma-clad Fe-Cr-C-based coatings. Full article

This study systematically investigated the effects of Co/Ni ratios (0.6–2.0) on the solidification behavior, as-cast microstructure, and element segregation of Co-Al-W-based superalloys, and elucidated the mechanism of thermodynamic and kinetic synergistic regulation. The results show that increasing the Co/Ni ratio has a negligible effect on the liquidus and solidus temperatures, but it significantly lowers the dissolution temperature of the γ′ phase, thereby expanding the alloy’s heat treatment window (HTW) from 215 °C to 269 °C. As the Co/Ni ratio increased from 0.6 to 2, the SDAS at the center of the alloy ingot decreased from 112.4 μm to 43.3 μm, resulting in a significant refinement of the as-cast microstructure. The dendritic segregation coefficients for positively segregating elements such as Ta, Hf, and Al, as well as negatively segregating elements such as W, all approached 1 significantly, effectively suppressing microsegregation during solidification. This study reveals the multidimensional synergistic regulation mechanism of the Co/Ni ratio on the non-equilibrium solidification behavior of highly alloyed Co-Al-W-based superalloys and quantitatively elucidates the relationship between the Co/Ni ratio, the microstructural uniformity of as-cast specimens, and the heat treatment process window. For the first time in a highly alloyed multi-component Co-Al-W system, a correlation has been established between the Co/Ni ratio, element segregation, dendrite coarsening coefficient, and heat treatment window. Full article

In the current work, the microstructural characteristics and corrosion performance of an Al-3.6Cu-1.0Li-0.40Mg-0.32Mn-0.12Zr alloy are correlated across different artificial aging regimes (150 °C, 160 °C, and 170 °C). In the under-aging stage, the corrosion depth increases with rising aging temperature, from 342.86 μm at 150 °C to 495.13 μm at 170 °C, indicating deteriorated corrosion resistance at higher temperatures. This trend is closely related to the significant increase in the proportion of the T1 phase in the matrix’s primary precipitate. Upon artificial aging for 24 h, the hardness increases gradually as the aging temperature rises. At higher aging temperatures, short-term aging hardness is higher, likely due to the formation of the T1 phase, which can also provide a strengthening effect. In contrast, the corrosion resistance of the alloy is enhanced at higher aging temperatures after 24 h of aging. These corrosion phenomena are closely related to the dominance of the θ″ phase during low-temperature aging and the gradual increase in the S′ phase during high-temperature aging. Furthermore, a transition from intergranular corrosion to pitting corrosion is identified at the high aging temperature of 170 °C with extended aging time. This corrosion mode transformation behavior is speculated to result from intermittent formation of magnesium segregation near the grain boundary, which alters the electrochemical heterogeneity between grain boundaries and the alloy matrix. Full article

CsPbI₂Br, an all-inorganic cesium–lead mixed-halide perovskite, has established itself as a leading contender for next-generation photovoltaics, owing to its near-optimal direct bandgap, exceptional thermal stability, and favorable optoelectronic characteristics. These attributes make it a versatile candidate for both high-efficiency single-junction devices and wide-bandgap top cells in tandem architectures with silicon or low-bandgap perovskites. However, the commercialization of CsPbI₂Br perovskite solar cells (PSCs) is severely hindered by inherent interfacial challenges, including halide segregation under operational stress, high density of interfacial defects, energy-level misalignment between the perovskite and charge transport layers (CTLs), and chemical incompatibility at hetero-interfaces. These factors limit power conversion efficiency (PCE) and long-term operational stability. Interface engineering has thus become the pivotal strategy to address these bottlenecks, enabling transformative improvements in device performance. This review comprehensively summarizes the state-of-the-art interface engineering strategies for CsPbI₂Br PSCs, including molecular passivation, construction of 2D/3D heterostructures, design of composite interlayers, and development of dopant-free, stable CTLs. The underlying mechanisms of defect passivation, non-radiative recombination suppression, energy-level alignment optimization, and ion migration inhibition are systematically elucidated. Furthermore, we discuss critical remaining challenges, including the trade-off between phase stability and optoelectronic quality, interfacial delamination due to thermal expansion mismatch, and scalable fabrication of interface-modified large-area devices. Finally, future research directions are proposed, emphasizing the development of multifunctional interfacial materials, all-inorganic interface architectures, in situ characterization combined with computational modeling, and integration into tandem photovoltaic systems. By consolidating current knowledge and highlighting promising frontiers, this review aims to guide the rational design of high-performance, stable, and commercially viable CsPbI₂Br PSCs, accelerating their role in the global transition toward renewable energy. Full article