In physical metallurgy, partially recrystallized microstructures show great potential for performance improvement through tailored thermo-mechanical processing. It is widely accepted that increasing the recrystallized faction generally reduces strength while enhancing ductility. However, deviations from this trend have long been recognized, stemming from competing effects of texture, dislocations, grain boundaries, and precipitates. These anomalies also raise an important question: can hidden factors beyond recrystallized fraction and aforementioned factors break the strength-ductility trade-off? Using machine learning, we identify the boundary between soft recrystallized and hard non-recrystallized regions as the determinant to the mechanical properties of partially recrystallized alloys. Through micro-digital image correlation (mu DIC), we verify that a pronounced strain gradient is generated near this boundary, which contributes to additional strain hardening capacity and ductility. The increased boundary density thus overcomes the strength-ductility trade-off in partially recrystallized alloys.

Dendritic segregation, ubiquitous microstructural inhomogeneity during solidification, severely deteriorates mechanical performance and processing stability. Despite advances in phase-field simulation, existing models often rely on oversimplifications (e.g., constant thermophysical parameters, dilute solution approximation, or binary-alloy bias), leading to inaccurate prediction of segregation behavior in industrial multi-component Mg alloys. To address this gap, a coupled computational framework is proposed via integrating the multiphase-field method, CALPHAD-based thermodynamic calculations, and a Taylor expansion-driven extrapolation algorithm for thermodynamic driving force. This framework enables high-fidelity simulation by capturing temperature-dependent thermophysical parameters and inter-solute interactions, while reducing computational complexity compared to conventional multi-component phase-field models. The model is systematically validated by evaluating non-constant vs constant thermophysical parameters, anisotropy coefficients, thermodynamic driving force, and solid fractions. Results show that the segregation intensity is dominated by partition coefficient (k) and diffusion coefficient (D), with smaller k and D causing severer segregation, and the multi-dendrite competition increases segregation ratios due to more solute accumulation. The segregation ratios increase with the undercooling and also the cooling rate. Despite different solute diffusivities, the segregation ratios of both Al and Zn decrease with increasing Al and Zn contents. The solute segregation of investigated elements ranks Zn > Gd > Y > Al. This work reveals the dynamic formation mechanism, morphology-segregation coupling, and multi-dendrite interaction inaccessible to simplified models (e.g., Scheil-type calculations), advancing fundamental understanding of dendritic segregation and providing an efficient tool for optimizing Mg alloy design.

The Ti-6.5Al-2Zr-1Mo-1V (TA15) alloy fabricated by laser powder bed fusion (LPBF) generally exhibits high strength but limited ductility, mainly owing to the dominance of alpha ' martensite within coarse columnar prior-beta grains. Achieving effective microstructure refinement via feasible and cost-effective heat treatment remains a critical goal for improving ductility. However, conventional heat treatment routines often lead to coarser alpha lath structures relative to the as-built martensite or require complicated processing routes. In this work, using a simple one-step annealing treatment, we successfully refined the microstructure of LPBF-fabricated TA15 alloy, significantly enhancing ductility with only a minor loss in strength. Following annealing at 800 similar to 850 degrees C for 2 h and subsequent furnace cooling, a well-refined lamellar alpha+beta microstructure was obtained. Compared with furnace cooling, water quenching further tailors the retained beta phase into distinct layers of considerable thickness. This refined microstructure delivers an excellent strength-ductility synergy: a tensile strength of 1058 MPa accompanied by a ductility of 20.4%, far exceeding the 10.2% elongation of the as-built alloy. Such abnormal microstructure refinement during single-step annealing is attributed to the temperature-dependent competition between alpha ' martensite decomposition and thermal coarsening. Specifically, within 800 similar to 850 degrees C, the decomposition of alpha ' martensite plays a dominant role in microstructure evolution, giving rise to lamellar refinement. This work demonstrates that a simple one-step annealing process can effectively regulate the as-built microstructure and achieve an outstanding mechanical balance, providing a practical and efficient approach for optimizing the mechanical performance of LPBF-manufactured TA15 components.

Designing precipitation-strengthened FCC/B2 dual-phase high-entropy alloys promotes the development of structural materials with high mechanical performance and lower density. In the present work, Ti and Ta were utilized as alloying elements in a Ni43.9 Co19 Cr10 Fe10 Al15 Mo2 B0.1 alloy to concurrently enhance the precipitation strengthening in both the FCC and B2 phases. In the FCC phase, the alloying elements increased the volume fraction of L12 precipitates and anti-phase boundary energy, thereby enhancing the precipitation-strengthening effect. In the B2 phase, the alloying elements promoted the formation of FCCstructured precipitates with refined inter-precipitate spacing and thus improved the Orowan strengthening contribution. With the harder B2 phase, the more significant hetero-deformation-induced hardening enhanced the alloy strain hardenability. Although ductility decreased, the continuous stacking fault glides and phase transformations in the FCC-structured precipitates contributed to the strength-ductility synergy by preventing intragranular cracking and mitigating crack propagation in the B2 phase. These findings provide valuable insights for the future design and development of precipitation-strengthened FCC/B2 dual-phase high-entropy alloys. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The non-uniform wall thickness of castings leads to substantial differences in cooling rates, which results in diverse solidified microstructures and ultimately affects mechanical properties. This study systematically investigates the effect of cooling rates spanning four orders of magnitude (10−2 to 102 K/s) on the solidified microstructural characteristics of Mg–Al alloy series (Mg–3Al to Mg–15Al). Through combining experiments and multivariate nonlinear regression analysis, a general power function relationship is established between the morphological characteristic parameters (equiaxed grain size λ1, specific surface area SS, dimensionless perimeter Pd, fractal dimension Fd, etc.), the alloy composition (C), and the cooling rate (R). λ1 follows λ1 = 61.05C−0.45R−0.31, decreasing with the increase of cooling rate; Ss conforms to Ss = 0.01C0.068R0.95, where high-Al content and rapid cooling can inhibit microstructure coarsening and significantly increase Ss; Pd follows Pd = 2.60C0.14R0.045 + 0.00014C0.41R2.19, and Fd satisfies Fd = 1.12 + 0.19C0.25R0.32. The step-quenching experiments are further employed to reveal the dynamic evolution law of solidification microstructures: the morphological complexity increases in the early stage of solidification but decreases in the later stage due to the dominance of coarsening. Meanwhile, a series of reliable predictive models are established to accurately predict the evolution of microstructural morphological parameters during solidification. Hardness analysis confirms that the hardness under different solidification conditions is significantly correlated with morphological characteristic parameters, providing a key basis for constructing the composition-microstructure-property relationship. The research results offer important theoretical support for the microstructure regulation and performance optimization of cast Mg–Al alloys.

Aluminum (Al) and titanium (Ti) are widely used for L12 precipitation, whereas niobium (Nb) promotes D022 precipitates formation. However, to regulate L12-D022 dual superlattices, Al and Ti are typically co-regulated as a compositional module in conjunction with Nb additions, which neglects their individual effects on precipitation behaviors. Our study systematically investigates the distinct effects of Al and Ti on L12-D022 dual superlattices formation through controlled individual additions in a Ni2.1CoCrFeNb0.2 high entropy alloy (HEA). At 0.5 at.% Al, L12 superlattice nucleates at D022/matrix interfaces, forming D022-L12 siamese-twin precipitates, while 1 at. % Al produces exclusive L12 precipitates. Conversely, Ti (1-2 at.%) yields isolated L12 precipitates within matrix with dominant D022 precipitates. These results demonstrate that Al drives D022 to L12 transformation whereas Ti maintains D022 stability while allowing discrete L12 formation. The HEA strengthened by siamese-twin precipitates achieves a balance strength and elongation, offering a design strategy for dual-superlattice strengthened HEAs.

Casting not only promotes the birth of early civilization but serves as the catalyst of the industrial revolution by raising productivity with bronze and iron. Although the achievement of strength-ductility synergy of casting alloy has been promoted by continual endeavor, it is still a challenge for casting alloys with superior specific strength beyond 200 MPa g-1 without the help of thermomechanical processing. Here, we screened a new composition and obtained a four-phase high-entropy alloy Ni36Fe34Cr10Al17Ti2Mo1 with a superior strength of 1630 MPa and elongation of 2.9% by a direct-cast approach. Surprisingly, the strength and ductility can be further increased to 1740 MPa and elongation to 8.7% via simple aging, with a historical specific strength of 242 MPa g-1 cm3. Improved strength arises from hierarchical microstructures with high-volume-fraction dual nanoprecipitates, and increased elongation arises from increased ductile FCC phase fraction and enhanced heterodeformation-induced stress.

The multi-principal element alloys (MPEAs) provide a broader compositional and structural design space for the development of metallic structural materials. In the Al-Cr-Fe-Ni system, subtle changes of composition can induce complex hierarchical microstructures, giving the opportunity to achieve excellent strength-ductility synergy. Here in this work, a series of Al14Fe20CrxNi66-x (x = 6, 9, 12, 15 at.%) MPEAs were designed and prepared by combining the Cr/Ni ratio modulation and thermomechanical treatment. The increasing Cr/Ni ratio triggers a transition from single FCC phase to FCC/B2 dual phase, and the B2 phase pins the FCC grain boundaries to refine grain size. Meanwhile, the increased Cr/Ni ratio alters the volume fraction and size of L1(2) and BCC precipitates on the nanoscale. The obtained multiscale hierarchical microstructure significantly enhances the room-temperature strength, raising the tensile strength from similar to 905 MPa to similar to 1233 MPa, with a slight reduction in elongation (similar to 32.0 %). The variation in Cr/Ni leads to the formation of a multi-scale heterogeneous structure, which induces the hetero-deformation induced strengthening effect, significantly enhancing the alloy's work hardening ability and ultimately achieving an excellent strength-ductility balance. This study systematically explores the composition-microstructure-mechanical property relationships, offering a pathway to engineer multiscale hierarchical microstructure in the Al-Cr-Fe-Ni system.

The non-equilibrium dendrite growth of Mg-6wt.%Al alloy during quasi-rapid solidification is studied by combining phase-field simulations and comparative experiments (furnace/air/water cooling: 0.07/2.9/181 K/s). The kinetic behavior of the solid-liquid interface is characterized, and the solute trapping-drag competition is emphasized. The effects of undercooling (28-36 K), cooling rate, and orientation angle (0-it/6) on dendrite morphological evolution are systematically explored, and the laws governing the morphological transition of the interface front are analyzed according to the condition criterion of interface transition. The experimental primary dendrite arm spacing decreases from-45 f 4.2 & micro;m (0.07 K/s) to-5.5 f 0.7 & micro;m (181 K/s), matching the phase-field simulations (relative error less than 9%). The solid-phase Al concentration rises from 2.6 0.22 wt.% to 5.4 f 0.26 wt.% experimentally, consistent with the simulated trends. The simulated critical value for planar-to-cellular transition (1.2 & times; 109 K & centerdot;s/m2) is lower than the theoretical value (1.48 & times; 1010 K & centerdot;s/m2) due to solute drag. The analysis of the partial drag condition is extended by integrating thermodynamics and kinetics. The limitation of the current model in capturing the intermediate partial drag state and potential future direction to address this are discussed. Through combining with the experimental results under different cooling rates, the simulation results are further interpreted and validated in both quantitative and qualitative way. This research provides theoretical basis for the regulation of magnesium alloy microstructures under quasi-rapid solidification such as industrial die-casting process.

To mitigate the high susceptibility to shrinkage porosity in Mg-10Gd-2Y alloys induced by their wide solidification temperature range, a pulsed magnetic field (PMF) is employed during solidification. By combining multiscale experiments and multiphysics simulations, this study systematically investigates the evolution of electromagnetic and flow fields and quantitatively characterizes the reconstruction of feeding channels within the alpha-Mg solid skeleton. The results reveal that the synergistic interaction of electromagnetic force, forced convection, and Joule heating not only refines the grains but, more importantly, reconstructs the feeding channels. Quantitative analysis of the three-dimensional network demonstrates that this reconstruction yields a significantly higher channel density, lower tortuosity, and enhanced branching connectivity. Permeability calculations confirm that these structural optimizations enhance liquid-feeding capability, with the improvement scaling positively with the PMF voltage. Consequently, under 150 V, the shrinkage porosity volume fraction decreases by 83.3%, while yield strength, ultimate tensile strength, and elongation increase by 20%, 25%, and 118%, respectively. Furthermore, a quantitative empirical correlation framework is constructed to bridge processing parameters (voltage), 3D defect topologies, and mechanical properties. This model decouples the contributions of shrinkage porosity features, identifying that the reduction of shrinkage porosity size and the optimization of its morphology are the dominant factors driving performance enhancement. Overall, this study creates a closed-loop framework that links external field parameters, microstructural quantization, and performance evaluation, providing both theoretical insight and an analytical framework for manufacturing highperformance magnesium alloy castings.

L12-strengthened FCC/B2 dual-phase high-entropy alloys (HEAs) exhibit excellent mechanical performance across a broad temperature range, positioning them promising candidates for hightemperature structural applications. However, microstructural coarsening and associated mechanical degradation under prolonged thermal exposure remain key challenges. In this study, a representative alloy with the composition Ni41.9Co19Cr10Fe10Al15Mo2Ti2B0.1 (at. %) was subjected to long-term aging at 800 degrees C, revealing an unusual microstructural evolution. Beyond the expected L12 coarsening within the FCC phase, an interfacial L12 shell formed via the progressive consumption of L12 precipitates from both the FCC and B2 phases, ultimately encapsulating the B2 domains. This transformation produced a unique three-level hierarchical architecture: FCC matrix with intragranular L12 precipitates, an interfacial L12 shell, and a B2 core. Remarkably, despite this pronounced microstructural evolution, the alloy maintained stable strength-ductility synergy from room temperature up to 800 degrees C. This stability is attributed to the additional strengthening imparted by the interfacial L12 shell and the favorable cooperative deformation among the FCC, B2, and interfacial L12 phases. A quantitative strengthening model was established, revealing that the strengthening contribution of the L12 shell increases with increasing shell thickness and exceeds 100 MPa after 720 h of aging. These results provide valuable guidance for the design of thermally stable precipitation-strengthened dual-phase HEAs for long-term hightemperature applications.

Ultrasonic assistance is widely employed to refine microstructures in additive manufacturing, yet its fundamental role during melt pool solidification remains insufficiently understood. By introducing high-power ultrasound into the melt pool during cold metal transfer wire and arc additive manufacturing (CMT-WAAM) of AZ31 magnesium alloy, this work reveals the spatially heterogeneous and dual roles of ultrasonic cavitation. Incomplete cavitation effect in the melt pool can lead to the retention of cavitation bubbles, significantly increasing the porosity of the melt pool after solidification, with shrinkage defects preferentially forming around retained cavitation bubbles. A framework describing bubble nucleation, growth, migration, and survival within the WAAM melt pool is established based on combined numerical simulations and theoretical analyses. Moreover, microstructural characterization reveals grain refinement in regions distant from cavitation bubbles, whereas bubble-adjacent regions exhibit grain coarsening accompanied by continuous precipitate networks. These results provide mechanistic insight into the concurrent beneficial and detrimental effects of ultrasonic cavitation, thereby offering guidance for optimizing ultrasonic-assisted additive manufacturing.

Modulating the multiphase microstructures is a key approach to enhancing the wear properties of metallic materials. Expanding upon the microcomposite nature of eutectic high-entropy alloys (EHEAs), we harness carbon alloying to synthesize nanoscale eutectic carbides in situ, while the resulting elemental repartitioning simultaneously tailors ultrafine BCC nanoprecipitates within the B2 matrix. This brand-new design of hierarchical nanostructures achieves a record-low dry wear rate of 1.15 × 10-5 mm3 N-1 m-1 among EHEAs. Highly dispersed M7C3 nanocarbides with strong interfacial bonding not only suppress surface nanocrystallization but also activate deformation twinning in the FCC phase for high deformation resistance. Furthermore, spherical BCC nanoprecipitates with near-zero lattice misfit enhance the elastic recovery of the BCC matrix and prevent crack initiation at the B2/BCC interfaces owing to negligible strain accumulation. These findings provide a controllable and scalable pathway for nanostructure tailoring, establishing a blueprint for synergistic dual-phase engineering in next-generation wear-resistant EHEAs.

Engineering compositional fluctuations in refractory high-entropy alloys (RHEAs) is critical for next-generation structural materials. However, there remains a lack of understanding regarding composition-driven phase evolution and its role in deformation mechanisms. This study reveals the influence of spinodal structure on dislocation dynamics and resolves the strength-ductility trade-off in RHEAs. Hybrid molecular dynamics (MD) and Monte Carlo (MC) simulations indicate that Mo substitutional solid solution in the TiVHfNb system induces compositional segregation and spinodal-modulated phases. The Ti41V27Hf13Nb13Mo6 RHEA achieves a yield strength of ∼1117 MPa and a ductility of ∼25.7 %, exhibiting a strength increase of ∼165 MPa compared to the base alloy without compromising ductility. With the addition of Mo, the increase in shear modulus enhances the solid solution strengthening effect, thereby elevating the yield strength. Slip trace analysis and TEM characterization reveal that Mo-assisted spinodal structure effectively promotes the activation of multiple slip systems and cross-slip behavior. On one hand, multi-slip facilitates frequent dislocation interactions and the formation of dislocation junctions, thereby enabling dynamic strain hardening. Stress relaxation tests further confirm that the spinodal structure plays a crucial role in retaining mobile dislocations, essential for sustaining plastic deformation. On the other hand, cross-slip initiated by the pinning effect mitigates strain localization, circumventing the conventional strength-ductility trade-off. This work provides critical insights for optimizing the mechanical properties of RHEAs.

Shear spinning is proposed as an industrially scalable route to engineer gradient dislocation architectures in the Fe40Ni36Al13Cr10Mo1 hypoeutectic dual-phase high-entropy alloy (DP-HEA), addressing the longstanding challenge of introducing high-density, non-uniform dislocation structures at engineering-relevant scales. The unique triaxial stress state activates multiple non-coplanar slip systems, generating a three-dimensional cellular dislocation network in the FCC matrix at a density of 4.54 & times; 10(15) m(-2), which is similar to 15% higher than that produced by conventional cold rolling (3.93 & times; 10(15) m(-2)). This high-energy defect state accelerates co-precipitation of coherent L12 and B2 phases during aging, with L12 contributing similar to 20% to the total yield strength versus similar to 15% in the cold-rolled-and-aged counterpart. The shear-spun-and-aged alloy achieves a yield strength of 1283 MPa, an ultimate tensile strength of 1512 MPa, and a tensile elongation of 8.2%, representing a similar to 61% enhancement over the solution-treated state and similar to 56 MPa above the cold-rolled-and-aged condition. A fundamental mechanistic transition from dislocation hardening (similar to 900 MPa) in the as-spun state to synergistic dislocation-precipitation strengthening after aging demonstrates shear spinning as a practical industrial strategy for concurrently tailoring dislocation configurations and precipitation kinetics to overcome the strength-ductility trade-off in multiphase HEAs.

Refractory high-entropy alloys (RHEAs) are promising candidates for high-temperature applications due to their intrinsic resistance to plastic flow softening at elevated temperatures. However, their brittleness makes it difficult to manufacture engineering components with complex geometries. Additive manufacturing via direct energy deposition (DED) technique offers flexibility in design and forming, yet processing defects caused by marked differences in the physical properties of the constituent multi-principal elements and the rapid solidification conditions associated with DED limit RHEAs' practical application. This study elucidates the formation of inherent defects, strategies for their suppression, and their influence on the mechanical response of a DED Ti41 V27 Hf13 Nb13 Mo6 RHEA prepared by mixed powders. Correlation of the molten pool characteristics to processing parameters reveals that laser power and scanning speed are pivotal in regulating defect formation. Insufficient energy input induces unmelted defects, rendering as-printed specimens brittle during tensile tests. Detailed microstructural characterization shows that the unmelted defects act as crack nucleation sites (through micropore coalescence), promoting premature failure. To address this, remelting (Strategy I) and high-energy density processing (Strategy II) were implemented via temperature field simulations and proved to be effective. The damage mechanism of the RHEA with moderate defects fabricated via Strategy I is primarily governed by cracking, whereas that of the low-defect-content RHEA produced via Strategy II is dominated by void nucleation. In the latter, reduced cracking effectively suppresses strain localization during deformation. The optimized RHEA exhibits a high tensile elongation of 17.9 % and a yield strength exceeding 1 GPa. These findings offer a framework to design ductile DED RHEAs by tailoring processing parameters to avoid defect-induced brittleness. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Eutectic high entropy alloys (EHEAs), combining excellent comprehensive properties with good castability, are promising materials. Hot working plays a pivotal role in refining the microstructure and enhancing the properties of EHEAs. This study investigated the hot deformation behavior of an Al13Cr10Fe40Ni36Mo1 hypoeutectic HEA via uniaxial compression tests at 1173-1453 K and strain rates of 0.05-5 s-1. The constitutive model was developed to describe the flow behavior, and the hot processing map was established via the Dynamic Material Model (DMM). Dynamic recrystallization (DRX) occurred in two domains 1423-1453 K at 0.5-5 s-1 and 1423-1453 K with 0.05 s-1. The FCC matrix underwent softening primarily through discontinuous dynamic recrystallization (DDRX), and the B2 matrix was softened mainly through continuous dynamic recrystallization (CDRX). At 1453 K, elevated strain rates facilitated the formation of Sigma 3 TBs, which promoted DRX in the FCC matrix. By correlating the processing map with the corresponding microstructures, the optimal hot working window was identified as 1423-1453 K and 0.5-5 s-1. This study contributes to advancing the industrial application and development of hypoeutectic HEAs.

Rapid solidification cellular structures in additively manufactured metallic materials have attracted considerable interest for their contribution to enhanced mechanical properties. In low-stacking fault energy (SFE) alloys, however, where extended dislocations dominate the cellular structure, the underlying formation mechanism and its influence on deformation behavior remain unclear. Here, we report a dislocation configuration, characterized by spatially dispersed stacking fault networks in a medium entropy alloy fabricated by laser powder bed fusion (LPBF), that enables a high strength-ductility synergy. The deformation mechanisms are investigated via weakbeam dark-field transmission electron microscopy. Our results demonstrate that the low SFE (similar to 21 mJ/m(2)) promotes the development of cellular structures dominated by extended dislocations, with their spatial distribution controlled by dislocation dynamics. Cellular structures act as preferential nucleation and extension sites for deformation faults, facilitating the formation of stacking fault ribbons (SFRs) and promoting faulting-induced plasticity. These cellular structures also facilitate the early activation of deformation twins (DTs). The high frequency of stacking fault interactions produces multiple types of stacking fault structures enriched with sessile stair-rod dislocations, thereby effectively enhancing dislocation storage and strain hardening capacity. The contributions of SFRs, DTs, and dislocation distribution to the strain hardening are also discussed. These findings provide fundamental insights into the role of dislocation configurations in the deformation mechanisms of additively manufactured alloys and offer a pathway for optimizing mechanical properties through dislocation engineering.