In this study, a Co-free Cr30Fe35Ni35 multi-principal element alloy (MPEA) with a single face-centered cubic (FCC) phase was fabricated by laser powder bed fusion (LPBF). Owing to its simple chemical composition and relatively low cost, the alloy shows promising potential for applications in cryogenic environments, particularly in nuclear engineering. The microstructure, mechanical properties, and deformation mechanisms of the alloy were systematically investigated at both room temperature (298K) and liquid nitrogen temperature (77K). The as-built LPBF Cr30Fe35Ni35 MPEA exhibits typical features of additive manufacturing, including cellular substructures and a high density of dislocations. At 77K, the alloy exhibits excellent strength-ductility synergy, with a yield strength of 1025MPa, an ultimate tensile strength of 1382MPa, and a total elongation of 47.6%. The remarkable enhancement in both strength and ductility at cryogenic temperature is attributed to the synergistic effects of high-density dislocations, deformation twins (DTs), microbands, and 9R structured phase, which collectively sustain a high strain-hardening capability in the Cr30Fe35Ni35 MPEA, effectively overcoming the conventional strength-ductility trade-off in metallic alloys.

Products designed for heat dissipation are often operated in elevated temperature environments. Therefore, understanding the microstructural variations, affected by heat treating processes, on thermal behavior at elevated temperatures is essential for the advancement of heat dissipation applications. Nevertheless, the temperature effect on thermal conductivity of magnesium alloys with different microstructures remains unclear. This study introduces an "intermetallic + alpha-Mg" two-phase model to clarify these effects in a Mg-7.28Al-0.13Y-0.11Mn (AW70) alloy. The thermal conductivity of assolutionized AW70 alloy is 55.1 W/(m & sdot;K) at ambient temperature, and increases to 68.2 W/(m & sdot;K) after aging, due to precipitation that reduces lattice distortion. As temperature rises, the thermal conductivity, in both solutionized and aged states, generally increases owing to consistent electron scattering by static lattice defects. The thermal conductivity of solutionized and aged AW70 alloy at 250 degrees C is about 79.2 and 91.2 W/(m & sdot;K) respectively, reflecting increase of 24.8 W/(m & sdot;K) (45.6%) and 22.2 W/(m & sdot;K) (32.3%) compared to the values measured at 25 degrees C. Both the solutionized and aged alloys exhibit a stable thermal conductivity increase rate (0.11 W/(m & sdot;K2)) below 250 degrees C, demonstrating a remarkable independence from variations in solute content and precipitates. Within the temperature range of 250-350 degrees C, the as-aged alloy shows a temporary decline in thermal conductivity, attributed to the dissolution of the Mg17Al12 precipitates into the alpha-Mg matrix. This research fills a gap in current understanding, while also sets the stage for further explorations in manipulating thermal properties of Mg alloys. (c) 2025 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Stabilizing the long-term oxidation behavior of Mg-rare-earth (RE) alloys at elevated temperatures is often hindered by localized scale damage that creates short-circuit transport paths. In this work, the oxidation behavior of an Mg-Gd-Y-Al alloy in solution-treated (ST) and extruded (EX) conditions is compared at 500 degrees C for up to 2000 h to elucidate how microstructural refinement governs the transition from protection to failure. Gravimetry reveals a sharp divergence in mass-change kinetics: ST reverses from mass gain to net mass loss, whereas EX maintains a near-plateau response, indicating markedly improved long-term stability. Extrusion refines the microstructure, reducing the average grain size from 24.3 to 4.9 mu m and the median second-phase size from 16.7 to 9.9 mu m. Multi-scale characterization-particularly FIB-SEM serial sectioning-shows that failure is highly localized and governed by crack/porosity connectivity rather than uniform scale thickening. In ST, coarse intermetallic second phases promote early interfacial debonding and cracking under coupled thermo-oxidative stresses, leading to percolating crack-porosity networks and penetrating defect channels that advance toward the substrate. Once formed, these channels provide potential short-circuit transport pathways, intensifying localized oxidation beneath spallation pits and accelerating interfacial degradation, ultimately causing extensive spallation and net mass loss. In EX, refinement and dispersion of second phases together with a fine-grained recrystallized matrix suppress sustained debonding and defect percolation, confining damage to a near-surface layer; the crack depth is limited to similar to 230 nm, with no through-thickness pathways detected. Overall, defect percolation and penetrating channels emerge as the microstructural origin of long-term oxidation instability, highlighting extrusion-enabled refinement as an effective route to stabilize Mg-RE alloys for high-temperature service.

Interfacial diffusion remains a major limitation for FeCrAl-coated Zr alloys considered for accident-tolerant fuel cladding. In this study, Fe-rich Fe79Cr15Al6 and Cr-rich Fe15Cr79Al6 coatings with a fixed nominal Al content of 6 wt% were prepared on Zircaloy-4 substrates by magnetron sputtering, followed by steam oxidation at 900 °C for 5000 s. The two coatings showed markedly different interfacial and oxidation responses. The Fe-rich coating underwent severe coating/substrate interdiffusion, extensive Zr transport through the residual coating, formation of a spinel-containing oxide scale with dispersed ZrO2, and internal oxidation of the Zr substrate. In contrast, the Cr-rich coating retained its columnar architecture and developed a continuous interfacial C15 (Fe,Cr)2Zr Laves layer with a mean thickness of 0.42 ± 0.16 μm. This layer was associated with suppressed outward Zr migration and limited inward penetration of coating elements, enabling formation of a thinner Cr2O3/α-Al2O3 scale. The results indicate that increasing the Cr/Fe ratio can promote interfacial Laves-layer formation and improve steam-oxidation tolerance. The large difference between the Fe-Zr and Cr-Zr eutectic temperature margins provides a useful framework for interpreting the observed contrast in interfacial stability.

The influence of grain boundary (GB) density on the 1200 degrees C steam oxidation of Cr coatings on Zr alloy was investigated. Coarse-grained coating with lower GB density exhibited superior protective capability compared to the fine-grained one. Degradation is fundamentally driven by outward Zr diffusion along Cr GBs, which triggers Cr2O3 reduction and forms an intergranular ZrO2 network that facilitates rapid oxygen ingress. Moreover, GB density dictates the oxide/metal interface evolution: a high density results in a planar interface with uniform scale consumption, whereas a low density confines reactions to discrete GB tips, forming a wavy interface with localized thinning. These findings highlight that reducing GB density is a critical strategy for enhancing the accident tolerance of Cr-coated Zr alloys.

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a high-throughput automated data acquisition technique with great potential for real-time data collection and analysis in automated STEM. However, its practical implementation is limited by challenges in data preprocessing, which hinder the timely and accurate interpretation of the large amounts of data it generates. Issues like pervasive noise, beam center drift, and elliptical distortions during high-throughput acquisition inevitably degrade diffraction patterns, leading to systematic errors in quantitative measurements. Conventional calibration algorithms are often material-specific and fail to provide a robust, generalizable solution. In this work, we introduce 4D-PreNet, an end-to-end deep-learning pipeline that integrates attention-enhanced U-Net and ResNet architectures to simultaneously perform denoising, center calibration, and ellipse calibration. The network is trained on extensive simulated datasets that cover a broad range of noise levels, drift magnitudes, and distortion types, thereby enabling generalization to experimental data obtained under different acquisition conditions. Quantitative evaluations demonstrate that 4D-PreNet reduces mean squared error by up to 50% in denoising and achieves sub-pixel center localization with average errors below 0.04 pixels. Compared to conventional algorithms, 4D-PreNet shows improved noise suppression and accurate restoration of diffraction features, enabling reliable real-time analysis of 4D-STEM data and supporting automated STEM workflows.

Extreme service environments, such as deep-space exploration and nuclear fusion reactor systems, require structural metallic materials with excellent cryogenic mechanical performance. In this work, a Co-free Al3Cr20Fe45Ni32 multi-principal element alloy (MPEA) was fabricated by laser powder bed fusion. The effects of laser power on the forming quality, microstructure and tensile properties were investigated, and the deformation mechanisms at 298 K and 77 K were systematically revealed. The alloy showed good processing stability within the investigated processing window, as the variation in laser power exerted only a limited influence on the tensile properties. Notably, the alloy exhibited a simultaneous increase in strength and ductility at 77 K. As the temperature decreases from 298 K to 77 K, the yield strength (YS), ultimate tensile strength (UTS), and total elongation (TE) increase from 627 MPa, 807 MPa, and 28.7% to 823 MPa, 1092 MPa, and 40.2%, respectively. The enhanced cryogenic mechanical performance was associated with a transition in deformation mode from dislocation slip dominated plasticity at 298 K to partial dislocation mediated deformation at 77 K. The activation of stacking faults (SFs), deformation twins (DTs), Lomer-Cottrell locks and 9R structure introduced abundant internal interfaces and promoted dislocation storage, leading to sustained work-hardening and delayed plastic instability. These findings provide new insights into the design of Co-free alloys with superior cryogenic strengthductility synergy through additive manufacturing.

Surface properties of crystals are critical in many fields, including electrochemistry and photoelectronics, the efficient prediction of which can expedite the design and optimization of catalysts, batteries, alloys etc. However, we are still far from realizing this vision due to the rarity of surface property-related databases, especially for multicomponent compounds, due to the large sample spaces and limited computing resources. In this work, we present a surface emphasized multi-task crystal graph convolutional neural network (SEM-CGCNN) to predict multiple surface properties simultaneously from crystal structures. The model is evaluated on a dataset of 3526 surface energies and work functions of binary magnesium intermetallics obtained through first-principles calculations, and obvious improvements are observed both in efficiency and accuracy over the original CGCNN model. By transferring the pre-trained model to the datasets of pure metals and other intermetallics, the fine-tuned SEM-CGCNN outperforms learning from scratch and can be further applied to other surface properties and materials systems. This study could be a paradigm for the end-to-end mapping of atomic structures to anisotropic surface properties of crystals, which provides an efficient framework to understand and screen materials with desired surface characteristics.

The long-term degradation of delta-ferrite and its interfaces critically governs the reliability of duplex stainless steel welds in nuclear environments, yet the mechanistic linkage between thermal aging and stress corrosion cracking (SCC) acceleration remains unresolved. In this work, we quantitatively establish how sequential delta/gamma interfacial degradation drives a sigmoidal ("delta-shaped") transition in crack growth kinetics during up to 30,000 h of thermal aging. Early aging (<15 kh) produces limited microstructural change, where spinodal decomposition and G-phase precipitation merely strengthen delta-ferrite without compromising interfacial integrity. A sharp kinetic transition emerges between 15-18.5 kh, as impurity segregation and carbide precipitation induce severe chromium depletion and interfacial embrittlement, triggering a three-order-of-magnitude surge in SCC crack growth rate (CGR). Beyond 20 kh, both microstructural and electrochemical degradation saturate, forming a steady yet highly susceptible interfacial state characterized by intense strain localization and high anodic activity. These results reveal that SCC acceleration is governed not by bulk embrittlement but by a time-dependent transition in delta/gamma interfacial chemistry and mechanics, establishing a mechanistic framework to predict and mitigate aging-induced failure in nuclear structural alloys.

The interfacial stability and degradation mechanisms of FeCrAl + Mo bilayer coatings on Zircaloy-4 were investigated during steam oxidation at 1000 degrees C for 5000 s above the Fe-Zr eutectic temperature. The Mo interlayer dramatically enhanced coating protectiveness, reducing Fe-Zr interdiffusion depth in the FeCrAl/Zr-4 system by more than two orders of magnitude. A protective dual-layer scale consisting of outer Fe(Cr,Al)2O4 spinel and inner alpha-Al2O3 was established on the coating surface. Nanoscale characterization revealed that the 2 mu m Mo interlayer was fully consumed, yielding a six-phase interdiffusion sequence of chi, R, (Mo,Cr)2(Fe,Zr) Laves, Zr(Fe,Mo,Cr)2 Laves, alpha-Zr(O), and prior beta-Zr. The topologically close-packed chi and R phases are distinctive consequences of the Fe component intrinsic to FeCrAl coatings, differentiating this system from Fe-free Cr/Mo/Zr architectures. A bidirectional degradation mechanism is revealed: flux imbalance on the coating side generates Kirkendall voids that accelerate internal oxidation and buried Cr2O3 formation, whereas sequential Laves phase formation on the substrate side preserves residual barrier function after Mo depletion. These findings recast Mo from a passive barrier into a sacrificial reaction layer and establish a mechanistic basis for designing next-generation diffusion barriers for accident-tolerant fuels.

The corrosion behavior of a FeCrNiAl dual-phase high-entropy alloy (DP-HEA) was examined in oxygen-deficient lead-bismuth eutectic (10-7wt% O) at 500 degrees C for up to 3000 h. The ordered B2-NiAl phase exhibited excellent stability, while the FCC matrix underwent severe Ni dissolution, driving an FCC -> Fe-rich BCC transformation with orientation inheritance. Upon cooling, dissolved elements reprecipitated sequentially as Fe-Cr intermetallics at the LBE interface, followed by Ni-Al precipitates at grain boundaries. These results establish a phase-dependent corrosion mechanism, wherein the NiAl phase acts as a stable skeleton and the FCC phase is highly susceptible to dissolution. The findings provide mechanistic insight into selective corrosion and phase evolution in DP-HEAs, offering guidance for alloy design in liquid-metal environments.

In this study, the hardening behavior of aluminum (Al) alloys subjected to heavy ion irradiation was systematically examined. Electron backscatter diffraction (EBSD) was employed to characterize the grain morphology and size distribution of the as-received materials. Ion irradiation was performed using 3 MeV Al2+ ions at 323 K to a nominal damage level of 35 dpa. Transmission electron microscopy (TEM) observations revealed a high density of nanoscale voids dispersed throughout the irradiated matrix, accompanied by pronounced entanglement of dislocation loops (DLs) within the peak damage region. A localized enrichment of both voids and DLs was further detected in the vicinity of precipitates and grain boundaries. The depth-dependent hardness of the irradiated alloys was evaluated through nano-indentation tests, which exhibited a distinct irradiation-induced hardening effect that gradually converged with increasing depth. To interpret these observations, a microstructureinformed hardening model was established, wherein distinct strengthening contributions were classified according to their relative impediments to dislocation motion. Comparison between experimental results and model predictions confirmed the model's capability to quantitatively reproduce the depth-dependent hardness profiles across different Al alloys. Furthermore, the model elucidated the relationship between the indentation size effect (ISE) and the evolution of dislocation density, while correlating the depth-dependent variations in void and loop densities with the corresponding hardening response. Theoretical analyses further identified the dominant hardening mechanisms governing the overall mechanical response and clarified their evolution as a function of indentation depth.

The long-term high-temperature oxidation resistance of multi-phase alloys critically depends on the structural integrity of the oxide scale; however, the influence of second-phase topological configuration on oxidation stability remains insufficiently understood. In this work, the oxidation behavior of Mg–8Gd–3Y–0.6Al alloys was investigated at 500°C for up to 3000 h to elucidate the role of mesoscopic connectivity in oxide-scale integrity. The solution-treated alloy, characterized by high mesoscopic connectivity of clustered second phases, exhibits a pronounced kinetic transition after ∼500 h, shifting from weight gain to rapid weight loss due to extensive scale spallation. In contrast, the rotary-swaged alloy exhibits a topological isolation state, maintaining stable, near-parabolic growth throughout the 3000 h exposure. Multi-scale characterization reveals that oxidation instability in the solution-treated alloy is closely associated with coarse second-phase particles, where geometric discontinuities promote localized stress concentration and microcrack initiation. Owing to the high mesoscopic connectivity of these second phases, the resulting defects evolve into percolating crack networks, thereby facilitating accelerated oxygen transport and progressive oxide-scale degradation. By comparison, rotary swaging induces fragmentation and spatial redistribution of second phases, effectively disrupting their connectivity and establishing topological isolation. This configuration suppresses the development of continuous crack pathways and, when combined with grain-refinement-induced rare-earth redistribution, promotes the formation of a continuous rare-earth-enriched layer. These results indicate that regulating mesoscopic second-phase connectivity through topological isolation, together with grain-refinement-induced rare-earth redistribution, provides an effective structural strategy for enhancing the long-term oxidation stability of Mg–RE alloys and related multi-phase systems.

Lightweight alloys, primarily based on magnesium, aluminum, or titanium, are characterized by their low density and high strength. They are widely used in industries operating under extreme conditions, such as aerospace, petrochemical, automotive, marine, as well as military and defense. Traditional design methods for these alloys often suffer from drawbacks such as an over-reliance on empirical intuition, long development cycles, and high costs. While more advanced approaches like integrated computational materials engineering (ICME) offer improvements, they frequently require substantial computational resources and may lack accuracy. Advances in computing power and algorithms have positioned artificial intelligence (AI) as a transformative tool in light alloy design, leveraging its strong data processing capabilities and reliable precision. This article first outlines the fundamental workflow and algorithms of data-driven methodologies. Furthermore, this review highlights key applications of AI in lightweight alloy design, focusing on property prediction and inverse design for conventional mechanical properties, corrosion resistance, high-temperature performance and other critical characteristics. Finally, it addresses current challenges, including incomplete inverse design frameworks, limited extrapolation capability, and difficulties in integrating domain knowledge. The concept of data scarcity is introduced, emphasizing the critical need for alignment between data and algorithms, and prospective research directions are discussed.

ABSTRACT Modifying solvents and additives to regulate cation solvation structures in electrolytes is a conventional approach, but the selection of solvents and additives suitable for rechargeable magnesium metal batteries remains limited. This study proposes a magnesium salt, magnesium (1 R ,2 R )‐1,2‐diphenylethane‐1,2‐diylbis(trifluoromethylsulfonylamide) (MgEDTF), featuring a chelating anion that modulates the solvation structure of Mg 2+ . Compared to the non‐chelating magnesium benzyl((trifluoromethyl)sulfonyl)amide (Mg(BnNTf) 2 ) analogue, the chelating anion of MgEDTF in 1,2‐dimethoxyethane (DME) enters the primary solvation shell to form an unsaturated [Mg 2+ –(EDTF 2− )–(DME)] complex. Distinct from the conventional [Mg 2+ –(3DME)] structure, this configuration facilitates the formation of an anion‐derived solid electrolyte interphase (SEI), thereby significantly reducing the Mg plating/stripping overpotential from 2.0 to 0.24 V. Moreover, trace halide additives synergize with the EDTF 2− anions to partially reconstruct the Mg 2+ solvation shell, forming an unsaturated [X − →Mg 2+ –(EDTF 2− )–(½DME)] (X − = Cl − , Br − ) structure. This configuration facilitates the formation of a more effective SEI by suppressing solvent decomposition, thereby further reducing the overpotential to below 0.20 V. This study demonstrates the feasibility of chelating anion‐mediated solvation in rechargeable magnesium metal batteries and provides a novel approach for solvation structure modulation in other metal‐based battery systems.

Due to the poor plasticity and deformability, magnesium matrix composites are difficult to strengthen using traditional severe plastic deformation (SPD) processes. In this study, we applied a large deformation of 0.36 to SiC particles reinforced Mg-Zn-Ca (ZX50/SiCp) composites at room temperature via rotary swaging (RS). The RS process significantly increased the yield strength of the composite from 174.1 MPa after extrusion to 346.5 MPa after RS with ten passes, representing a 98% enhancement. The remarkable strengthening effect was primarily attributed to grain boundaries strengthening, dislocation strengthening and precipitation strengthening effects. The results indicated that the average grain size of the composite refined to 16 µm after ten passes, and a substantial number of deformation twins were developed in the host grains. The interactions between twin boundaries and precipitates as well as reinforcement particles blocked the twin growth, resulting in dense twin networks. With increasing strain, multiple twins developed to further refine the twin lamella. Furthermore, the activation of numerous dislocations developed dislocation arrays and the geometrically necessary dislocations (GNDs) density increased from 2.8 × 10¹⁴ to 7.2 × 10¹⁴ m⁻². In addition, dynamic precipitation occurred during the RS process, resulting in the formation of substantial nano-scale Mg-Zn second phases (average diameter ∼70 nm). The severe shear strain during the RS process promoted the uniformly dispersion of reinforcement particles. These findings provide valuable insights into the fabrication and strengthening of magnesium matrix composites through the proposed RS process.

The paper investigates the diffusion-induced grain boundary migration (DIGM) in six Fe-Cr-Ni ternary alloys exposed to steam at 480 degrees C. DIGM occurs due to the outward diffusion of Fe and Cr, essential for surface oxide formation, resulting in DIGM regions depleted in Fe and Cr and enriched in Ni. A significant finding is the tendency for preferential intergranular oxidation (PIO) to occur along these migrated grain boundaries, attributed to their enhanced element diffusivity. The extents of DIGM, PIO, and surface oxide thickness exhibited notable variations across the alloys with varying Ni contents, ranging from 11 wt.% to 75 wt.%. Further theoretical analysis and diffusion-barrier modeling were introduced to clarify the mechanistic role of Fe/Ni. The results reveal that Ni content modulates the competing diffusion behaviors of Fe, Cr, and Ni along grain boundaries, leading to a compositional transition from Fe-dominated to Ni-dominated diffusion regimes. The increasing Ni concentration reduces surface oxide thickness, thereby diminishing local diffusion and influencing the extent of both PIO and DIGM. However, due to the strong coupling among DIGM, PIO, and surface oxidation, their evolution with Ni content exhibits a complex, non-monotonic trend that is difficult to quantify precisely. This complexity arises from the interplay between oxidation-driven chemical potential gradients and composition-dependent grain boundary diffusivity. Generally, DIGM promotes PIO unless the outward and inward diffusivity of elements is significantly affected by surface oxides. However, in high corrosion-resistant alloys, DIGM inhibits the occurrence of PIO by facilitating the formation of an external protective chromia layer through enhanced Cr diffusion outwards.

Cr-coated Zr alloys have become a competitive candidate for accident tolerant fuel (ATF) cladding due to the dense coating structure and stable performance. However, the influence of primary water chemistry on the long-term fretting corrosion behavior of Cr coatings remains poorly understood. This work aims to untangle the effects of dissolved hydrogen (DH) and dissolved oxygen (DO) on grid-to-rod fretting corrosion behavior in simulated primary water condition. The results demonstrate that water chemistry plays a decisive role in fretting damage evolution, leading to opposite wear trends. Under DH conditions, fretting wear progressively stabilizes with cycling, whereas DO accelerates fretting and triggers an unstable fretting behavior. Although the crevice geometry partially restricts oxygen ingress, DO can still locally penetrate the contact interface. Furthermore, DO promotes the formation of mechanically weak oxide films and induces localized porous dissolution at defect and pore tips within the Cr coating, causing the transition from stable adhesion-dominated wear to unstable fracture-dominated wear. These findings provide mechanistic insight into the environmentally assisted fretting corrosion behavior of Cr-coated claddings and clarify the critical role of DO in destabilizing long-term fretting performance.