In this work, a coupled multiscale microstructural design strategy was developed for a Cu-5Ni-0.7Si-0.4Al alloy by integrating partial recrystallization-induced grain heterogeneity with hierarchical precipitation. Partial recrystallization produced heterogeneous grains spanning the micrometer to submicrometer scale, while Ni-Si–Al alloying promoted a site-dependent precipitate hierarchy, including intergranular δ-Ni2Si, intragranular δ-Ni2Si, and nanosized Ni-Al-enriched precipitates consistent with an L12-ordered structure. The resulting architecture is inferred to regulate dislocation motion and improve strain compatibility during deformation. The optimized alloy achieves a yield strength of 800 MPa, an ultimate tensile strength of 840 MPa, an elongation of 15%, and an electrical conductivity of 38% IACS.
Predicting the yield strength of refractory high-entropy alloys at ultra-high temperatures remains a major challenge. Here, we couple a physics-based edge-dislocation model with a residual multilayer perceptron to learn systematic strength corrections. The resulting hybrid framework significantly improves predictive accuracy in the ultra-high-temperature regime and reveals interpretable correlations between residual strengthening and distortion-related descriptors, providing an efficient route for the rapid screening of RHEAs with superior strength retention.
Combining quasi-in-situ EBSD and FIB-aided surface study, this work unveils the mechanisms of dynamic recrystallization (DRX) and superplastic deformation in an as-rolled Al-Cu-Li alloy. At early deformation stage (ϵ = 50%), low-angle grain boundaries and banded grains dominate, with superplastic flow governed by intragranular dislocation slip (IDS). With increasing strain, continuous DRX through dynamic recovery and sub-grain rotation resulting in a fully recrystallized structure, enhancing grain boundary sliding (GBS) and strain rate sensitivity. As the main superplastic deformation mechanism of the second stage (ϵ = 300%), GBS is mainly accommodated by local DRX and IDS.
Honeycomb-like heterostructural titanium matrix composites (HTMCs), featuring soft Ti6Al4V cores and hard TiB/Ti6Al4V composite shells, were fabricated. The HTMCs with various cell sizes (Φ1.0, Φ0.8, Φ0.5, Φ0.4 and Φ0.3) exhibit higher work hardening rates (WHRs) than homogeneous counterparts. The superior WHR is attributed to the activation of pyramidal dislocation slip near the hetero-interfaces, as well as strain delocalization, which postpones tensile necking. The tensile strength and uniform elongation of Φ0.5 (991 MPa, 7.66%) are increased by 10.5% and 96.9% compared with the Ti6Al4V alloy. A smaller cell size weakens the WHR because the grains within the soft core region are refined.
Ultrahigh-strength steels often suffer from limited resistance to plastic instability, restricting lightweight structural applications. Here, a 1.5 GPa quenching and partitioning (Q&P) steel containing 10 vol.% austenite exhibits appreciable ductility and sustained work hardening. Combining in-situ neutron diffraction with microscale strain mapping, we track the dynamic evolution of local stress and strain during deformation. The initially soft austenite hardens rapidly, and its phase stress eventually exceeds that of the martensite matrix. This strength reversal continuously redistributes local strain, promotes strain delocalization and delays plastic instability, offering a new strategy to design ultrastrong ductile alloys through dynamic stress/strain partitioning.
Heterostructured materials provide an effective pathway for overcoming the conventional strength-ductility trade-off. This work introduces TiN-mediated heterostructured nanoprecipitates into laser-clad Fe50Mn30Co10Cr10 metastable high-entropy alloy coatings to couple grain refinement, FCC stabilization, and staged TRIP/TWIP-assisted deformation. The TiN addition promotes the in-situ formation of TiN-mediated core–shell nanoprecipitates containing TiN-rich shells, 9R-like domains, and MnTi2O4-rich regions. These nanoprecipitates refine the solidification microstructure, stabilize the metastable FCC matrix, and provide effective barriers to dislocation motion. Among the freestanding coating specimens, the 2TiN condition exhibits the best strength-ductility synergy, achieving a UTS of ∼1062 MPa and a total elongation of ∼22.8%.
Site-specific grain-structure control is desirable for turbine blades with region-specific performance requirements. Here, we demonstrate that a columnar-to-equiaxed transition can be initiated in electron-beam additive manufacturing within individual melt pools and retained through controlled overlap ratio and melt pool geometry. A high overlap ratio with shallow melt pools increases grain density and suppresses competitive dendritic growth, yielding near-equiaxed grains with an average size of ∼30 μm on single-crystalline substrates. A tailored heat-treatment protocol incorporating optimized recovery annealing relieves stresses while preventing recrystallization, thereby stabilizing the refined microstructure. This strategy enables grain structure design without altering established alloy compositions.
Overcoming the strength–ductility trade-off remains a central challenge for titanium matrix composites, because ceramic reinforcements often induce severe interfacial stress concentration and premature cracking. Here, we develop a hierarchical heterostructure in Ti–6.5Al–2Zr–1Mo–1 V through in-situ reaction and subsequent hot extrusion, consisting of nanoscale TiB reinforcements, primary α, β phase and secondary α. The pronounced hetero-deformation-induced strengthening and activation of [Formula: see text]c + a[Formula: see text] dislocations enable the composite to achieve 1351 MPa tensile strength and 15.9% elongation, representing increases of 40.1% and 26.2% over the matrix alloy, respectively. This strategy offers a scalable route for designing high-performance titanium composites.Highlightsαp, β, autocatalytic αs and in-situ-formed nanoscale TiB jointly constitute the HHS composite.The HHS delivers 1351 MPa tensile strength and 15.9% elongation.Multiple deformation mechanisms collectively sustain the work-hardening capacity.TiB-assisted strain accommodation alleviates local stress concentration.
Investigating the synergistic effects is important for understanding the roles of the alloying elements and designing new kinds of superalloys. Understanding the dislocation mechanism is crucial for elucidating the Re-W synergistic strengthening effect in nickel-based single crystal superalloys. In this work, the interaction between clusters and dislocations was investigated using interrupted tensile tests combined with transmission electron microscopy (TEM) characterization. The results show that Re-W clusters hinder the motion of dislocations, trigger double cross-slip and promote the formation of dislocation tangles. This process enhances both the strength and the work hardening of the alloy.
This study reports a novel dual gradient-structured (GS) Mg–2Zn–0.8Gd (wt.%) alloy fabricated via surface sliding friction and followed by heat treatment. Excellent grain boundary (GB) stability is achieved through the co-segregation of Zn and Gd atoms. The segregated gradient structure produces an excellent strengthening and work hardening effect, which is attributed to the combined effects of prominent GB segregation within the GS layer and the recovery of dislocation storage capacity. Furthermore, a remarkable segregation hardening in the surface layer increases the hard–soft disparity, which arouses more geometrically necessary dislocations that further synergistically strengthen and toughen the alloy.
A Zr-rich Ti-Zr-Nb-V-Mo-Al metastable β titanium alloy was developed via high-to-low two-step aging to achieve a superior strength-ductility synergy. Two-step aging produced a bimodal α microstructure composed of coarse primary α laths and high-density fine secondary α precipitates with coherent α/β interfaces. The Aged-2 alloy exhibited a yield strength of ∼1.48 GPa, an ultimate tensile strength of ∼1.56 GPa, and a total elongation of ∼11%. Post-deformation STEM/TEM analyses revealed that coarse α laths accommodated dislocations, whereas fine α precipitates promoted dislocation interactions and strain hardening. This bimodal α architecture provides an effective strategy for strengthening Zr-rich β titanium alloys.
Metal Additive manufacturing (MAM) enables the fabrication of geometrically complex, high-performance components but suffers from nonlinear process-structure-property relationships, defect formation, and costly optimization. This review systematically evaluates machine learning applications across the MAM lifecycle, including process parameter optimization, defect detection and monitoring, material property prediction, and intelligent design. It further explores frontier advances in physics-informed learning, explainable artificial intelligence, and digital twins for closed-loop control. By identifying critical hurdles such as data scarcity, limited interpretability and real-time implementation, this paper provides a strategic roadmap toward a reliable and intelligent MAM process.
High-temperature strain softening limits the application of lightweight refractory multi-component alloys (LRMCAs) in aerospace and nuclear engineering. This study reports an anomalous strain-hardening behavior in a non-equiatomic Ti60(V2Zr3Nb2)34Al6 (A6) LRMCA at 450 °C. The alloy's strain-hardening rate increases by approximately 119%, while its true ultimate tensile strength remains nearly unchanged, as compared with room temperature. A thermo-mechanical-coupling-induced BCC→HCP structural transformation mechanism is revealed. Thermal activation and deformation defects synergistically drive the diffusionless transition, and in-situ formed nanoscale HCP phases pin dislocations via the Orowan mechanism. This work establishes a new pathway for designing high-performance LRMCAs with improved high-temperature softening resistance.
The insufficient thermal stability remains a bottleneck for the broader application of high-strength Al–Zn–Mg(–Cu) alloys. Here, we develop a novel low-Zn/Mg alloy where clusters exhibit preferential growth and smooth compositional continuity with T-type precipitates, enabling efficient cluster-to-precipitate transformation and resulting in high-density thermally stable T-type precipitates. Therefore, the developed alloy achieves a yield strength of ∼515 MPa and retains ∼430 MPa (>80%) after long-term thermal exposure at 150°C for 1000 h, significantly outperforming conventional age-hardenable Al alloys. This work proposes a composition-matching strategy between clusters and precipitates for developing high-strength and heat-resistant Al alloys.
The atomic-scale evolution from Guinier-Preston (G.P.) zones to multi-modal MgZn precipitates, i.e. rod-like [Formula: see text]-MgZn2 (P63/mmc and Cmcm), rod-like [Formula: see text]-Mg4Zn7 (C2/m), lath-like [Formula: see text]-MgZn2 (P63/mmc) and disc-like [Formula: see text]-MgZn2 (P63/mmc) during ageing in a Mg-8Zn-1Al-0.5Mn alloy has been systematically investigated. Rod-like and lath-like [Formula: see text]-MgZn variants originate from spherical and newly discovered strip-like G.P. zones governed by Zn-vacancy complexes, respectively. Furthermore, Mg6Zn7 substructural units mediate multidirectional irregular stacking with C14/C15-MgZn2 substructural units to generate rod-like [Formula: see text]-MgZn, while single C14-MgZn2 substructural units enforces ordered stacking, yielding lath/disc-like MgZn2. These insights into precursor-mediated MgZn precipitation provide a foundation for designing high-performance Mg-Zn alloys.
Anomalous shear is an unusual mode of plastic deformation in body-centered cubic (BCC) metals, traditionally associated only with dislocation slip. Here, we show it can also arise from deformation twinning. Using in situ transmission electron microscopy straining and atomistic simulations, we find twins on [Formula: see text] planes at low resolved shear stresses nearly half those for the primary systems. These anomalous twins originate from screw dislocation transformations and are dominant when sheared in the anti-twinning direction. They promote dislocation emission, enable relaxation-induced detwinning, and substantially enhance deformability. Our findings establish anomalous twinning as a previously unrecognized plasticity mechanism in BCC metals.
Ni-based single crystal superalloys for turbine blades experience multimodal creep. Current microstructural design lacks tailored γ-γ′ microstructures for specific conditions. Five initial microstructures with similar morphology and varying γ′ size were creep tested under 980°C/250 MPa and 1100°C/137 MPa. Both conditions showed single-peak creep life evolution, but the creep life peak shifted toward smaller γ′ sizes under the higher temperature. This shift arises from coupled effects of γ′ size on dislocation motion, lattice misfit on interfacial dislocation density and extra damage from TCP phase, offering insights for optimizing microstructures under complex service conditions.
Understanding defect induced damage accumulation within, and at the surface, of materials and structures is critical to assuring their structural integrity and performance. This work couples synchrotron radiation X-ray computed tomography with high-contrast laser speckle pattern full-field surface strain mapping by digital image correlation to correlate internal defect evolution and surface strain development during tensile straining of the AM titanium aluminide. This comparative analysis reveals strong spatial and temporal correlations relating defect growth to the local strain, providing a new means to observe both the 3D internal and 2D external behaviour of materials under a variety of in-service environments.IMPACT STATEMENTThis paper proposes the synchronous correlative application of X-ray CT and laser speckle DIC for in-situ testing of materials, relating internal structural changes to surface strain evolution.
B2 precipitates strengthen lightweight steels, but their morphology has been treated only descriptively. Here, we show that the B2 aspect ratio, tuned by annealing time, dictates the deformation pathway and strain-hardening rate. Partial recrystallization yields elongated ellipsoidal B2 (aspect ratio ∼3) on residual dislocations, promoting planar slip, dislocation entanglement, slip refinement, and microband-induced plasticity, sustaining a higher strain-hardening rate across the entire plastic regime. Full recrystallization produces spherical B2 (aspect ratio ∼1), which limits deformation to planar slip, slip bands, and deformation twinning activated at a later stage of deformation, with a comparatively lower strain-hardening rate after yielding.
