{1122} twinning is widely activated in alpha-titanium (alpha-Ti) to accommodate the strain along the c-axis. The short, three-layer height bands are observed along {1122} twin boundary, but the formation mechanism and atomic structure of these bands are in debate. In this work, we characterized atomic structure of these bands by using high-angle annular dark-field scanning transmission electron microscopy. Combining with topological analysis and first-principles density functional theory calculations, our conclusion is that these bands have a distorted w-phase structure. The formation of the distorted w-structure can be treated as the dissociations of a three-layer twinning disconnection (b3, 3h{1122}), where a leading partial disconnection (1/2b3, 3h{1122}) and a trialing partial disconnection (1/2b3, 3h{1122}) are bounded by a distorted w-structure. Correspondingly, we proposed possible mechanisms for twin thickening via partial disconnections. These findings enhance the fundamental understanding of twinning behavior in hexagonal metals.

Achieving high recoverable energy density (Wrec) with near-unity efficiency (η) in lead-free dielectrics remains a major challenge for advanced pulse power capacitors, given their central role in emerging pulsed power systems and high-voltage electronics. Here, we show that targeted engineering of dynamic dipole behavior provides an effective route to remarkable energy storage performance. Guided by phase-field simulations, we design (Bi0.5Na0.5)TiO3 (BNT)-based multilayer ceramic capacitors that transform a continuous network of strongly correlated dipoles into discrete nano-domains. Within each nano-domain, dipoles retain strong local cooperativity, which maintains high polarization while markedly suppressing hysteresis losses. As a result, the optimized multilayer ceramic capacitors (MLCCs) achieve a recoverable energy density of 16.2 J cm-3, an η of 98.5%, and a record-high figure of merit (WF) of 1080 at 650 kV cm-1. This moderate operating field also produces an ultrahigh energy storage strength (ξ) of 249 J kV-1 m-2, highlighting the efficiency of the dipole-regulation strategy. These findings demonstrate that weakly correlated and dynamic dipoles can be harnessed to advance high-performance, lead-free energy storage devices and offer a viable design principle for next-generation capacitive technologies.

ABSTRACT Many metallic components are frequently subjected to coupled environments of friction and vibration, stemming from interfacial contact and relative motion between mating parts or external stimuli. Consequently, it is imperative for these components to exhibit a synergy of high wear resistance and superior damping properties. In this study, a Ti 2 Ni/NiTi dual‐phase alloy with exceptional wear resistance and damping performance was in situ alloyed using the electron beam directed energy deposition (EB‐DED) process, employing pure Ti and Ni wires as raw materials. Within the three‐dimensional configuration, the NiTi martensite phase exhibits an island‐like morphology, embedded within a continuous network of the Ti 2 Ni phase, featuring an approximately equal phase ratio. This dual‐phase structure effectively harnesses the respective advantages of the Ti 2 Ni phase and the NiTi martensite phase. In friction scenarios, the hard Ti 2 Ni phase acts as a load‐bearing framework to resist the wear, whereas the NiTi martensite phase can deform to minimize wear and recover from deformation upon heating, demonstrating self‐healing capabilities. Under vibration conditions, the NiTi martensite phase dissipates energy through the movement and rearrangement of twin boundaries, resulting in effective damping. This dual‐phase structure shows promising potential for applications where friction and vibration coexist. Moreover, the phase ratio of Ti 2 Ni and NiTi can be flexibly tailored by EB‐DED technology through the regulation of wire feeding speeds, allowing for the on‐demand balance between wear resistance and damping performance.

Strong yet ductile Ti alloys are crucial for aerospace and biomedical applications. While low-alloy Ti systems reduce dependence on expensive alloying elements, they often suffer from poor mechanical performance. We demonstrate the development of high-strength low-alloy (HSLA) Ti by leveraging the highly non-equilibrium processing conditions of additive manufacturing to control diffusive phase transformations. This approach enables the formation of hierarchical microstructures in Ti-Cu alloys, featuring micron-sized grains with refined laths and finely dispersed nanoprecipitates. The resulting structural hierarchy effectively impedes dislocation glide and promotes multislips, delivering ultra-high strength without compromising ductility. A Ti-5Cu alloy with dual nanoprecipitation achieves an exceptional ultimate tensile strength of 1,340 MPa and 12% elongation to failure, outperforming most commercial Ti alloys. These results highlight the transformative potential of additive manufacturing to develop more sustainable Ti systems that are strong, ductile, low-alloyed, and costeffective.

Enhancing dielectric energy-storage density (Ue) requires maximizing the difference between maximum and remanent polarizations (ΔP). Improving ΔP remains fundamentally challenging, as existing strategies rarely achieve simultaneous high maximum polarization and low remanent polarization. We introduce a postsynthesis treatment method, cryogenic thermal cycling, in which liquid nitrogen infiltrates the film and then is rapidly cycled to 100°C. This process markedly increases ΔP to 105 microcoulombs per square centimeter in oxide ferroelectric titanate films through oxygen vacancy-mediated nitrogen hybridization. Using this approach, we increased Ue to 261 joules per cubic centimeter with an efficiency approaching 80%. This approach is broadly applicable to diverse film materials with thicknesses spanning the nano- to microscale, offering a facile and cost-effective route to overcoming the critical bottleneck in ΔP and Ue.

The manufacture of nanostructures on silicon (Si) has profound implications across diverse disciplines. Previous research has focused mainly on qualitative explanations based solely on evidence from electromagnetic and matter reorganization theories. This study designed experiments and explored the characteristics of nanostructures created by scanning with an ultrafast laser, in which experimental evidence supporting both electromagnetic and matter reorganization theories was simultaneously observed. Four distinct surface morphologies were identified, each with specific formation thresholds: 0.06, 0.09, 0.22, and 0.27 J⋅cm−2. The polycrystalline Si that emerged at the apex of the monocrystalline Si matrix was directly characterized, and the occurrence of SiO2 and α-Si was detailed. The simultaneous and distinct contributions of electromagnetic and reorganization theories were revealed. By examining the relationship between phase transitions and laser features, the conditions under which each mechanism operates were established. This study provides novel insights into the precise control of Si nanostructures, which could revolutionize applications in electronics, photonics, and materials science.

Enhancing the fatigue resistance of metals remains a significant challenge in materials engineering. This study demonstrates that titanium exhibits remarkable fatigue resistance when heterostructures are introduced via additive manufacturing. Compared to homogeneously structured titanium, heterostructured titanium shows a remarkable 141% improvement in fatigue strength and a 53% enhancement in fatigue ratio. The heterostructure promotes the formation of high-density geometrically necessary dislocations, leading to hetero-deformation-induced strengthening under cyclic loading. This process enhances structural stability, suppressing fatigue crack initiation and propagation, thus improving fatigue resistance. These findings suggest that heterogeneity is a promising strategy for enhancing fatigue resistance across various alloy systems.

The dislocation cellular structure is a typical microstructural feature in additively manufactured alloys. A persistent debate surrounds how dislocation cellular structures strengthen materials. This study, utilizing in-situ tensile straining transmission electron microscopy, unveils the presence of two distinct types of cell walls, differentiated by the presence or absence of discernible crystallographic misorientations across the cell walls. Cell walls with misorientations act as dislocation sinks and absorb dislocations, whereas cell walls without misorientation hamper dislocation motion by forest dislocation entanglement. These contrasting cell wall-dislocation interaction mechanisms lead to different structural stabilities of cell walls. Cell walls with misorientations tend to maintain their structural integrity during deformation, while cell walls without misorientation are prone to dissolution under high strain. These deformation behaviors suggest that the dislocation cellular structure enforces both dislocation hardening and boundary hardening mechanisms, contingent on the type of dislocation cell walls. This study further demonstrates that by varying additive manufacturing parameters, the fractions of different types of cell walls can be adjusted, thereby enhancing the overall mechanical properties.

The interface coherence between precipitates and the matrix-whether coherent, semi-coherent, or incoherent-significantly impacts both the strength and ductility of metallic materials. An optimal balance between these properties can be achieved through manipulation of the precipitate/matrix interface. In this study, 1 wt.% and 2 wt.% TiN nanoparticles were introduced into a laser powder bed fusion (LPBF) fabricated CoCrMoW alloy as a reinforcing phase. Compared to the unreinforced alloy, the alloy with 1 wt.% TiN exhibited substantial improvements in yield strength, ultimate tensile strength, and fracture elongation, increasing from 876 MPa, 1190 MPa, and 15 % to 1071 MPa, 1421 MPa, and 17 %, respectively. Although the addition of TiN nanoparticles did not significantly affect the average grain size, it inhibited the formation of fine grains at the fusion line and influenced the overall grain size distribution. More importantly, the incorporation of TiN nanoparticles during the LPBF process led to the in-situ formation of semi-coherent precipitates rich in Ti and N, as well as coherent precipitates rich in Ti, N, and O. The semi-coherent precipitates, which exhibit well-defined orientation relationships and periodic misfit dislocations, enhanced strength by blocking stacking faults and epsilon laths. They also preserved plasticity by promoting self-relaxation through twinning at intersected areas, thus preventing crack nucleation at the interface. Furthermore, the chemical inhomogeneity between the coherent phase and the matrix increased resistance to dislocation cutting of the precipitates, thereby improving the material's strength without compromising ductility. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Heterostructured alloys have recently gained prominence due to their exceptional capability to simultaneously enhance strength and ductility. However, despite these mechanical improvements, the properties of such alloys typically conform to the rule-of-mixtures, whereby the overall performance falls between that of the hard and soft zones. This work explores how the inherent thermomechanical mismatch induced during additive manufacturing can be leveraged to surpass this limitation. In a layered Ti-3.5Al/Ti-6Al-4V heterostructure, the substantial thermomechanical mismatch between the constituent layers led to significant thermal expansion/ contraction differences during rapid thermal cycling and solidification. This process generated pronounced thermal mismatch stresses and promoted dislocation accumulation at the interfaces. These interfaces facilitated hetero-deformation-induced strengthening, governed by substantial back-stress effects and effective strain accommodation within the soft Ti-3.5Al layers. Furthermore, fractographic analyses confirmed that the soft Ti3.5Al layers effectively arrested and deflected cracks, thereby mitigating premature fracture. These combined mechanisms resulted in strength for the Ti-3.5Al/Ti-6Al-4V heterostructure that exceeds that of both homogeneous Ti-3.5Al and Ti-6Al-4V, while maintaining sufficient ductility. This outcome breaks the rule-of-mixtures observed in typical heterostructured alloys. Consequently, this research demonstrates an innovative approach to utilizing additive manufacturing-induced thermomechanical mismatch for designing high-performance titanium alloys, offering a pathway for property enhancement beyond conventional optimization strategies.

Interfacial degradation, oxidative damage, and fatigue cracking pose persistent challenges to structural alloys operating in the intermediate-temperature regime (400–600 °C), often resulting in accelerated wear and premature failure. To address this, we design a multicomponent Ti-containing eutectic high-entropy alloy (EHEA) via additive manufacturing (AM) and targeted Ti alloying to engineer a thermally stable, refined microstructure tailored for enhanced tribological performance. The resulting alloy achieves an ultralow wear rate of 6.20 × 10⁻⁵ mm³/N·m at 600 °C—approximately 86

Ultra-high temperature ceramic composites (UHTCCs) with low density and exceptional heat resistance are essential for hypersonic vehicle applications, enabling increased payload capacity and higher Mach numbers. However, developing a fabrication process that enables UHTCCs with both lightweight and superior thermal protection performance is still a challenge. To tackle this problem, in this study, a combinatorial process of vibration-assisted slurry impregnation and polymer infiltration pyrolysis was developed to fabricate gradient lightweight Cf /ZrB2 -SiC composites, consisting of continuous carbon fiber fabric, ZrB2 -SiC and a carbon aerogels (CAs) layer. The resulting composites exhibit a low density of (0.62- 0.96 g cm-3 ) but excellent oxidation and ablation resistance, which can withstand ultrahigh temperatures between 2100 degrees C and 2500 degrees C. The porous Cf /CAs layer, with a density of 0.38 g cm-3 and specific bending and compressive strengths of 43.47 MPa/(g cm-3 ) and 15.53 MPa/(g cm-3 ), respectively, provides both structural integrity and lightweight properties to the Cf /ZrB2 -SiC composite. Furthermore, the density of the composites can be precisely tailored by adjusting the thickness of the Cf /ZrB2 -SiC layer, allowing for customized fabrication to meet diverse service environment requirements. This flexibility highlights the adaptability of the combined processing techniques. The unique combination of controllable low-density properties and exceptional oxidation and ablation resistance endows gradient lightweight Cf /ZrB2 -SiC composites are promising as lightweight, ultra-high temperature thermal protection systems for hypersonic vehicle applications. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Precipitation hardening is a well-known strategy that can raise the yield strength of alloys to well over 1 GPa, including at 77 K, but is less potent in offering strain hardening than twinning/transformation-induced-plasticity (TWIP/TRIP) mechanisms, which have been essential for the high ductility and fracture toughness of established cryogenic alloys. Here we demonstrate an innovative strategy to tailor the coherent nanoprecipitates by purposely designing negative-curvature interfaces (NCIs). This morphological control uses the geometric curvature and curvature-gradient effects to generate additional local stress, high elastic energy density, and substantial strain gradients to make NCIs prolific sources of dislocation nucleation. The proliferation of partial dislocations builds up ultra-dense hierarchical stacking-faults dynamically all over the deforming volume, substantially enhancing strain-hardening and toughening. The resulting NiCoCrAlTa alloy exhibits excellent cryogenic mechanical properties, achieving a high yield strength of 1.26 GPa, a product (~90 MPa%) of ultimate tensile strength (~1.80 GPa) with tensile ductility (~50%) and a fracture toughness of 213 MPa·m1/2 at 77 K-representing a record-high combination among all reported alloys to date. Our interface design strategy may be applicable to all precipitation-hardened alloys, transforming the precipitates from merely passive strengtheners to active and tunable agents regulating the plastic flow.

Multi-component elemental eutectic high-entropy alloys (EHEAs), exemplified by AlCoCrFeNi2.1, have emerged as promising structural materials due to their unique dual-phase B2/FCC lamellae microstructures and resulting exceptional mechanical properties. However, there are still certain limitations in tailoring the microstructure of EHEAs using conventional methods. Laser additive manufacturing (AM) techniques offer significant opportunities to customize chemical and microstructural heterogeneities across multiple scales, thereby enhancing alloy properties, facilitated by extreme non-equilibrium kinetics. AM effectively refines the eutectic lamellae architecture and enhances interface density, thereby upgrading mechanical properties, service properties, and functional properties, which far surpass those of conventionally processed counterparts. For instance, in the as-built state, laser powder bed-fused AlCoCrFeNi2.1 typically achieves a yield strength of 900–1100 MPa, approximately 30–50% higher than its as-cast counterpart, while also exhibiting superior wear and corrosion resistance. However, previous works are rather scattered across various aspects, including composition, processing, microstructure, and properties, in the AM-ed AlCoCrFeNi2.1 system. This review systematically revisits the effects of alloying, processing strategy, temperature, and post-treatment on the microstructural evolution, deformation behavior, strengthening mechanisms, and various performances of the AM-fabricated EHEA system, establishing the process-structure–property relationships. Furthermore, future research directions are proposed to fully exploit the potential of AM-EHEAs in demanding engineering applications.

Development of lead-free dielectric capacitors with simultaneously high recoverable energy-storage (ES) density (Wrec) and breakdown strength (Eb) is hindered by a fundamental constraint; although high Eb permits large electric fields, conventional ferroelectrics suffer from premature polarization saturation, limiting further enhancement of Wrec. We demonstrate a mechanism-guided strategy for Bi0.5Na0.5TiO3 (BNT)-based relaxor ferroelectric ceramics, centered on optimized polar nanoregion (PNR) responses and delayed polarization saturation. Phase-field simulations show that interconnected rhombohedral/tetragonal (R/T)-related PNRs with appropriate size and dynamic responsiveness can be progressively activated under electric fields, enabling delayed polarization saturation, sustained ΔP growth, and low hysteresis loss. Guided by this mechanism, compositional disorder, R/T phase coexistence are integrated in the BNT-based system to construct an optimized PNR landscape. The optimized multilayer ceramic capacitors deliver a record ES potential (ξ = Wrec/Eb) of 278 J kV-1 m-2, together with a high Wrec of 26.4 J cm-3 at 950 kV cm-1 and 89% ES efficiency. Atomic-resolution microscopy confirms pronounced local chemical heterogeneity and coexisting R/T-related PNRs, consistent with the optimized PNR response predicted by phase-field simulations. These results establish a generalizable framework for overcoming the intrinsic ξ-Eb trade-off and advancing next-generation high-Wrec dielectric capacitors for ES and pulsed-power applications.

Achieving ultrahigh energy storage in lead-free dielectric ceramics is fundamentally constrained by the intrinsic trade-off between large polarization and high dielectric breakdown strength. Here, we establish an interpretable machine-learning-guided design framework that quantitatively links ionic descriptors with polarization behavior in ABO3-based dielectric matrices, enabling the rational identification of compositions with intrinsically high polarization potential. Guided by this strategy, a (Bi0.275Na0.2255K0.0495Ba0.3)(Ti0.985Hf0.015)O3-0.15(La0.5Sm0.5)2Ti2O7 (BNBT-3) composition is discovered that exhibits an exceptional maximum polarization of 50.19 µC cm-2. When processed via a viscous polymer process, the resulting BNBT-3-VPP capacitors achieve an ultrahigh breakdown strength of 1400 kV cm-1 and a recoverable energy density of 25.1 J cm-3 with high efficiency, placing them among the best-performing lead-free dielectric ceramics reported to date. Structural characterization combined with phase-field simulations reveals that the outstanding performance originates from polarization-lattice decoupling, where nanoscale polarization clusters and multiphase coexistence suppress long-range ferroelectric order while enabling reversible polarization rotation. This work establishes a generalizable strategy that integrates interpretable machine learning with physically grounded materials design, providing a powerful route for discovering high-performance dielectric energy storage materials.

Hot extrusion is a critical manufacturing technology for tailoring microstructure and eliminating metallurgical defects of powder metallurgy (P/M) superalloys in industrial applications. However, the complex coupling between severe plastic deformation and adiabatic heating challenges the prediction and precise control of microstructures. To address this challenge, this study proposed a synergistic end-to-end framework integrating a continuous strain-gradient high-throughput extrusion technique with physics-constrained interpretable machine learning. The established paradigm enables the rapid acquisition of microstructural evolution data under a wide strain range of 0-2, facilitating the determination of grain refinement limit of 3.63 & micro;m at the strain of approximately 1.0. By leveraging the explicit kinetic formulas mined by symbolic regression, we quantitatively decoupled the competing contributions of dynamic recrystallization (DRX) and thermally activated grain growth. The kinetic analysis demonstrates that the grain refinement during the initial stage is primarily governed by the concurrent activation of multiple DRX nucleation ways and dynamic precipitation of primary gamma' precipitates at grain boundaries. Then, the adiabatic deformation heat-driven gamma' redissolution and subsequent grain growth dominated the later stage after the saturation of DRX. These findings challenge the conventional 'larger strain, finer grain size' consensus during extrusion, providing a generalizable optimization strategy for metal extrusion processing that extends beyond the specific case of superalloys.

ABSTRACT Flexocatalysis provides an alternative route for converting mechanical energy into electrical energy through flexoelectricity, thereby avoiding the crystal‐symmetry constraints that limit conventional piezocatalysis to non‐centrosymmetric materials. In this study, strong flexocatalytic effects were established in reduced strontium titanate (R‐STO) nanoparticles prepared by a facile solid‐state reduction route. Regulated generation of oxygen vacancies generates near‐surface lattice distortion and a gradient in lattice strain, which together give rise to substantial flexoelectric polarization, and thus R‐STO demonstrates an excellent capability for Rhodamine B (RhB) decomposition, achieving > 78% degradation within 45 min. The kinetic rate constant of R‐STO (0.0307 min−1) is nearly double that of pristine STO (0.0163 min−1), primarily due to enhanced charge separation and prolonged electron–hole pair lifetimes induced by the flexoelectric polarization. R‐STO also exhibits an impressive co‐catalyst‐free hydrogen production rate of 380.8 μmol/g/h, representing a fourfold increase over pristine STO (94.5 μmol/g/h). This enhancement is attributed to synergistic effects of improved charge separation and transfer, a favorable band structure, and optimized adsorption configurations during catalysis. These results underscore the promise of flexocatalysis for applications in environmental remediation and renewable energy production.

Antiferroelectric ceramics are promising for next-generation electrostatic energy storage, yet their performance is fundamentally constrained by the trade-off between high energy storage efficiency (η) and large recoverable energy storage density (Wrec), arising from the antiferroelectric-to-ferroelectric phase transition and associated hysteresis loss. Here, we show that a combination of engineered local polarization disorder and high-field operability enables a highly favorable balance of these metrics. In PbZrO3-based ceramics, we introduced controlled compositional heterogeneity that broadens polarization vector distributions while preserving the antiferroelectric modulation. Phase-field simulations and experiments indicate that this engineered disorder spatially distributes the switching fields associated with the antiferroelectric-ferroelectric transition, thereby reducing polarization hysteresis while maintaining high polarization strength. As a result, the multilayer ceramic capacitors achieve Wrec = 23.2 J cm-3 and η = 98.1% at 167 kV mm-1, corresponding to a figure of merit of 1220, surpassing most reported state-of-the-art multilayer ceramic capacitors under comparable high-field conditions. These findings highlight local polarization disorder as a key mechanism that, in combination with enhanced breakdown strength, enables ultrahigh energy storage performance and offers a promising route toward high-performance capacitive energy storage for advanced pulsed-power applications.

Cryogenic alloys simultaneously achieving ultrahigh yield strength (YS ≥ 2.0 GPa) alongside substantial uniform elongation (UE) are critically needed, yet fundamentally constrained by the strength-ductility trade-off. Guided by Eshelby's inclusion theory, we reconcile this challenge by designing a novel hierarchical nano-ordering (HNO) architecture within an ultrafine-grained NiCoCr-based multi-principal element alloy, fabricated via combining additive-manufacturing and tailored post-processing. The HNOs-featuring a controlled size distribution and interfacial properties-comprise dispersed incoherent σ-dispersoids (~70 nm), a high density of bimodal coherent L12 precipitates (~5 and 26 nm) and widespread, highly-distorted local-chemical-orderings (~0.7 nm). This configuration introduces a stepwise increase in elastic strain energy, which in turn triggers the sequential activation of potent dislocation sources. The resulting mobile dislocations engage in extensive and varied interactions with the nano-orderings during deformation, thereby activating cooperative strain-hardening mechanisms. These nano-architectures thus function simultaneously as dislocation generators, strain-hardening enablers, and strengthening agents. Consequently, this HNO-mediated self-hardening and self-ductilizing mechanisms yield an exceptional cryogenic (77 K) property set: YS of ~1.96 GPa, ultimate tensile strength of ~2.35 GPa, and UE of ~22%, surpassing both the cast counterpart and all previously reported advanced alloys. This strategy establishes a transformative paradigm for designing ultrastrong-yet-ductile materials through integrated manufacturing approaches.