Elucidating the rapid solidification mechanisms in multi-principal element eutectic alloys remains a critical challenge. This study systematically explores the rapid solidification behavior of newly developed CoNiSn0.6 eutectic medium-entropy alloy (EMEA) through in situ high-speed high-resolution imaging and characterizes its microstructures in detail by electron backscatter diffraction, revealing the nucleation mechanisms and growth modes governing microstructure evolution during non-equilibrium solidification. More generally, a consistent crystallographic orientation relationship (OR) between FCC phase and HCP phase, i.e., {112(sic)0}(HCP)//{11(sic)1}(FCC), < 0001 >(HCP)//< 110 >(FCC), is exhibited. Furthermore, twin ORs are observed in the HCP phase. At low undercooling, the twin OR is {112(sic)1}(1(sic)1(sic)26), whereas at intermediate undercooling, the twin ORs {112(sic)1}(1(sic)1(sic)26), {112(sic)4}(2(sic)2(sic)43) and {101(sic)2}(1(sic)011) are observed between HCP phase in different colonies. A significant finding is that, at high undercooling, the HCP phase exhibits four distinct crystallographic orientations with mutual misorientations of approximately 70(degrees)/ < 112(sic)0>. Based on this discovery, it was revealed for the first time that the FCC solid solution phase preferentially nucleates within the melt, while the HCP phase grows concurrently with the FCC phase rather than undergoing a solid-state phase transformation, thereby leading to the HCP phase with the aforementioned specific orientation relationship. Notably, both lamellar and anomalous eutectic microstructures demonstrate coupled growth. In light of these novel findings, which have not been systematically documented in the prior studies, the rapid solidification process of CoNiSn0.6 EMEA proceeds via a single nucleation mode. This investigation deciphers the fundamental mechanisms underlying eutectic solidification in multi-principal systems, offering critical perspectives for tailoring high-entropy alloy microstructures through non-equilibrium solidification pathways.

Surface cracks in integral structures of aircraft pose a significant threat to structural integrity. This paper investigates the three-dimensional propagation behavior and crack-arrest characteristics of surface-initiated cracks in the web of an integral wing spar manufactured from 7050-T7451 aluminum alloy. A three-dimensional finite element model is developed in ANSYS 2024R2 to evaluate the stress intensity factors (SIFs) along the crack front under representative displacement-controlled loading conditions. This paper focuses on comparing the crack-arrest effectiveness of different tear strap configurations by varying their height-to-thickness (H/T) ratios while maintaining a constant mass. The results indicate that surface crack propagation in the spar web is dominated by Mode I (opening mode). Among the investigated designs (H/T = 0.5, 2.0, and 8.0), the configuration with the smallest ratio (H/T = 0.5) exhibits the most effective crack-arrest capability, yielding the lowest crack-driving force as the crack approaches the strap. Furthermore, fatigue life estimates based on Paris' law illustrate the dependence of remaining service life on the evaluated stress intensity factor evolution. These findings provide a comparative basis for the damage-tolerant design of integral metallic aircraft structures, suggesting that selecting appropriate geometric proportions for crack-arrest features can enhance resistance to surface crack propagation.

Cr-related impact abrasive wear behavior of wear-resistant steels was investigated. The steels were quenched at 1040 °C and tempered at 540-600 °C. Hardness and impact toughness were measured using hardness tester and an impact testing machine, respectively. Dynamic load abrasive wear tests were conducted. Microstructure was characterized. It was found that Cr3 (3 wt. H_m ) into traditional three-body abrasive wear model, V_abr = A.ω /H_m , by which the relationship between impact abrasive wear loss and Vickers hardness was interpreted.

Hydrogen transported by mobile dislocations serves as a critical link between hydrogen embrittlement mechanisms and hydrogen-induced fracture in high-strength martensitic steels. The static experimental evidence can be observed from the fracture microstructure, however, the evaluation of hydrogen-dislocation interactions during dynamic process is still lacking. In this study, the in situ tensile-hydrogen desorption method was applied to examine the hydrogen desorption behavior of martensitic steels including different microalloying elements (V, Nb) and the dislocation-mediated hydrogen desorption factor (mu) was defined to quantify the dynamic interaction capacity between hydrogen and dislocations. The results indicated that the mu value in Nb-steel was lower than that in V-steel, suggesting that less hydrogen was transported by moving dislocations during the deformation process and the lower susceptibility to dislocation transport of hydrogen in Nb-steel. This work establishes a novel path to evaluate the dynamic interactions between hydrogen and dislocation, offering new insights into hydrogen embrittlement mechanism and fracture behavior in high-strength steels.

Cold-drawn pearlitic steel wires exhibit among the highest yield strengths achieved in steels, arising from the complex interplay between plastic deformation and microstructural evolution. Among the contributing mechanisms, the dissolution of cementite plays a critical role, yet its underlying mechanism remains unclear. In this mechanistic study, we applied advanced microscopy to a model pearlitic steel before and after severe plastic deformation to elucidate the role of dislocations in this phenomenon. Results show that dislocations interact with cementite lamellae intensively, leading to their segmentation and partial amorphization, together with the formation of low-angle grain boundaries in ferrite. Concurrently, carbon is found to redistribute along dislocations and grain boundaries in regions where cementite shears, highlighting the role of dislocations in the dissolution process of cementite. As a result, the accumulation of supersaturated carbon and the dislocations promote further amorphization, thereby alters deformation behaviors and accommodates local plasticity. This work contributes to the understanding of strain-induced phase transformation in heterogeneous lamellar microstructures and highlights its potential in achieving an exceptional synergy of strength and toughness in ultrahigh-strength steels.

The nonoxidative coupling of methane (NOCM) offers a promising route to convert methane into value-added chemicals. Liquid metals have emerged as potential catalysts for NOCM, due to their propensity against coke formation and the flexible atomic arrangement that facilitates methane activation, with liquid state indium (In) gaining attention. However, the reaction pathways and catalytic mechanisms of In during NOCM have yet to be fully understood. Here, we report the discovery of locally generated In liquid metal active sites on In2O3 for the NOCM reaction, supported by silicon dioxide substrates, in the vicinity of an in situ formed In silicon oxide (In2Si2O7) interfacial layer. By the implementation of combined in situ transmission electron microscopy and electron energy loss spectroscopy, we directly observed the formation of liquid metal "In active sites", near the interfacial layer, at >600 °C. The spectroscopy analysis reveals that In2Si2O7 is a reservoir in methane conversion, storing reactive H* and CH x * intermediate spillover from "In" for driving the NOCM reaction, avoiding the overcracking of CH4 over metallic In. This finding provides a practical approach for the rational design of efficient and noncorrosive liquid metal-based catalysts.

In aerospace, transportation, and other critical industries, the development of high-strength, high-ductility Al-Zn-Mg Al alloys with superior resistance to hydrogen embrittlement (HE) remains a pivotal challenge with substantial practical implications. However, the long-standing issue of HE induced by H accumulation at susceptible interfaces, including grain boundaries (GBs) and semi-coherent precipitate interfaces, has remained inadequately addressed. Here, we propose a strategy of local H partitioning that leverages Cr doping to introduce the E phase (Al18Cr2Mg3) and eta phase (Mg(Zn,Cr)(2)). The E phase not only consumes Mg segregated at GBs to mitigate H enrichment but also acts as a hydrogen trap. The Cr-rich eta phase formed by Cr substitution enables conversion of the weak hydrogen trap MgZn2 into the strong hydrogen trap Mg(Zn,Cr)(2). The maximum H trapping energy in Mg (Zn,Cr)(2) (0.60 eV/atom) exceeds that at its semi-coherent interface (0.56 eV/atom) and at GB (0.25 eV/atom), driving thermodynamically favorable H migration from hazardous interfaces to the benign interior of nanoprecipitates. Experimentally, Cr-doped Al alloys exhibit nearly threefold enhancement in HE resistance under similar to 6.7 ppmw H charging compared to standard-state Al alloys, with the area fraction of hydrogen-induced intergranular fracture (IGF) reduced to zero and complete elimination of IGF. This is mainly attributed to the mitigation of H enrichment at the interfaces, thus inhibiting the H-driven stacking fault (SF) expansion and planar slip at GBs. The strategy of suppressing HE by manipulating local H partitioning via microalloying, rather than preventing H ingress, offers a more reliable and simpler solution to ensure the service safety of high-strength Al alloys in H-related application scenarios.

Conventional hot work dies steels experience a deterioration in toughness and hardness above 550 degrees C, owing to the coarsening of carbides and elemental segregation as well as degradation of sorbite. To address this limitation, we conceptualized and designed a DNA steel. By tempering at 580 degrees C, DNA steel achieved a peak hardness of 57.3 HRC together with an unnotched impact energy of 353.5 J. Ultimate tensile strengths of DNA steels at 25 degrees C and 580 degrees C were 1936 MPa and 1572 MPa, respectively. Both were 428 MPa and 506 MPa higher than those of 8418 die steels at corresponding temperature. Observation by high resolution TEM testified that the increase in strengths at ambient and elevated temperatures stems from the fully coherent regime of predominant continuous precipitation (CP) of ordered B2 type NiAl precipitates (average 12 nm in size) with lattice coherency coefficient (LCC) of 0.31%. Coherency and order strengthening by CP covered nearly 85% contribution of strength increment. In contrast, after tempering at 620 degrees C, discontinuous precipitation (DP) became dominant, accompanied by precipitate coarsening (LCC approximate to 0.83%, size > 30 nm) and formation of Laves phases. This resulted in reduction of dislocation storage capacity and concentration of localized strain (impact energy drops from 354 J to 98 J).

In this study, 0.23-mm-thick nitrided sheet of low-temperature, high-magnetic-induction grain-oriented silicon steel was used as the experimental material. Two heating rates, 10 and 15 ℃/h, were applied during high-temperature annealing, and samples were extracted at selected temperatures between 1020 and 1100 ℃. The effects of the heating rate on the evolution of the Goss texture and (Al,Si)N inhibitors, as well as on the magnetic properties during secondary recrystallization, were systematically investigated. The results showed that the slower heating rate promoted more complete dissolution of the inhibitors, thereby reducing the grain-boundary pinning force and facilitating the abnormal growth of Goss grains. Consequently, secondary recrystallization proceeded more completely, and the Goss texture intensity was enhanced. Moreover, the sample annealed at the slower heating rate exhibited a higher fraction of misorientations in the range of 20°–45°, which provided favorable crystallographic conditions for grain-boundary migration and the preferential growth of favorably oriented grains, thereby promoting the earlier onset of abnormal Goss grain growth. In contrast, the faster heating rate resulted in insufficient inhibitor dissolution and predominantly caused inhibitor coarsening. The resulting strong grain-boundary pinning force delayed the onset of secondary recrystallization and weakened the Goss texture, leaving fine misoriented grains in the final product. Consequently, the magnetic induction B800 of the sample annealed at the slower heating rate reached 1.881 T, which was significantly higher than that of the sample annealed at the faster heating rate. This study elucidates the mechanism by which the heating rate regulates the secondary recrystallization behavior of low-temperature, high-magnetic-induction grain-oriented silicon steel and provides a theoretical basis for optimizing the high-temperature annealing process.

The present study revealed the intrinsic mechanism of post-deformation (relaxation after deformation) ferrite transformation and validated that manipulating grain size and volume fraction of ferrite enhances strength-ductility synergy in a low-carbon martensitic steel. In-situ neutron diffraction and microscopic investigations uncovered that austenite to ferrite transformation preferentially occurs at austenite grain boundaries during relaxation due to localized dislocation concentration. According to the in-situ neutron diffraction measurements, the retained dislocation density was obviously higher than the level before deformation during relaxation at 755 degrees C. Conversely, dislocation density could fully decrease to the level prior to deformation during relaxation at 765 degrees C. Thermodynamic calculations demonstrated that high chemical driving force with sufficient dislocations effectively enhances nucleation and coalescence of similarly oriented grains. Meanwhile, the stored dislocations during relaxation govern the types of transformation behaviors. Therefore, distinct transformation behaviors allow precise tuning of ferrite microstructural features: grain size and volume fraction. This strategy, leveraging the heterogeneity in grain-boundary transformation by holding various relaxation times, increases the mechanical properties of low-carbon martensitic steel. These findings provide valuable microstructure design concepts for overcoming the strength-ductility trade-off in high-strength martensitic steels. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Two-dimensional tungsten disulfide (2D WS2) has attracted significant attention across diverse application fields, particularly optoelectronic devices and field-effect transistors, due to its exceptional properties. A thorough elucidation of the WS2 growth mechanism is crucial for device implementation, as it allows for precise modulation of the nanoscale properties. Despite significant efforts toward the growth of 2D WS2 for increasing its size, detailed investigations into its structural evolution, especially for the out-of-plane layered WS2, remain scarce. In this work, we identify two distinct conversion growth mechanisms for in-plane and out-of-plane layered WS2 using a homemade chemical vapor deposition (CVD) system. We systematically investigate the evolution of different WS2 nanophases by altering the precursor and regulating the sulphur concentrations. The results reveal that out-of-plane 1D and 2D WS2 are formed via an outside-in mechanism during the layer-by-layer sulphurization of WO2.7 nanowires, while in-plane layered WS2 evolves from WO3 precursors via a 'self-seeding' mechanism involving an island-like WO3-x-WS2 core-shell structure. This study clarifies the 2D WS2 growth process, offering key insights into the evolution mechanisms of low-dimensional WS2. These findings may not only pave the way for synthesizing high-quality, large-scale 2D-domain WS2 but also offer guidance for the controlled growth of other transition-metal dichalcogenides.

As a significant branch of NiTi shape memory alloys (SMAs), Ni-rich NiTi alloys have garnered considerable research attention. This study employs Ti45Ni55 (at.%) alloy wires to prepare dual-way SMA springs under various annealing temperatures via deformation-aging constraint methods, focusing on optimizing their phase transformation behavior, cyclic stability, and electrothermal driving performance under thermo-mechanical coupling. The results indicate that the phase transformation sequence of the alloy wire evolves with annealing temperature (400-550 degrees C), progressing from B2 -> R to B2 <-> R <-> B19 ' and ultimately to B2 <-> B19 ' transition, accompanied by generally decreasing phase transformation temperatures. Optimal superelasticity (residual strain < 0.2 %) with distinct stress plateaus is achieved at 400-450 degrees C, while higher annealing temperatures reduce platform stresses but increase residual strain. The SMA spring annealed at 500 degrees C demonstrates superior actuation performance under thermomechanical coupling (3 N-1.5A), achieving maximum actuation displacement (73.9 +/- 5.1 mm), fastest response (1.12 +/- 0.2 s), and excellent fatigue resistance. Thermal hysteresis expansion correlates with increased A(f)* and decreased R-f*. The minimal lattice distortion of R phase enables low-energy, high-speed actuation with enhanced cyclic stability. Functional degradation arises from residual stress, dislocation accumulation and concurrent nanocrystalline coarsening, which collectively destabilize the shape memory effect and martensitic transformation. These findings provide critical insights for designing high-performance SMA actuators through microstructure optimization.

In this study, novel non-equiatomic CoCrFeMnNi-based medium- and high-entropy alloys (M/HEAs) were designed to activate distinct deformation mechanisms, including twinning-induced plasticity (TWIP) and/or transformation-induced plasticity (TRIP). Tensile tests were performed at 298 and 173 K. A variety of ex-situ multiscale characterization techniques, strengthening modeling, thermodynamic modeling (CALPHAD method), and ab initio density functional theory (DFT) calculations were employed to investigate the structural and microstructural evolution, enabling accurate identification of the strengthening and active deformation mechanisms operating in the M/HEAs. Strengthening modeling revealed that grain boundary strengthening was the primary contributor to yield strength at both temperatures. A key finding of this study is that a controlled FCCHCP martensitic transformation, associated with TRIP, enhances the strength-ductility balance even when the resulting HCP phase reaches similar to 50% volume fraction. This demonstrates that TRIP-enabled metastability engineering is a promising strategy for designing high-performance M/HEAs for next-generation structural applications in energy, aerospace, and defense.

Functional fatigue limits the reliable application of NiTi shape memory alloy actuators, yet the mechanism by which Cu addition stabilizes electrothermal cycling remains insufficiently clarified. Here, Ti49Ni46Cu5 shape memory alloy springs annealed at 400-550 °C were electrothermally tested under a constant load of 3 N and a current of 1.5 A. Among the investigated conditions, the 400 °C-annealed spring retained a stable one-step B2 ↔ B19′ transformation after 500 cycles, whereas higher annealing temperatures induced changes in the transformation sequence. This stable transformation pathway indicates that cyclically generated defects and residual stress exert a weaker perturbation on the transformation response. Microstructural characterization further shows that grain-boundary Ti(Ni,Cu)2 precipitates pin local slip and restrict dislocation accumulation during thermomechanical cycling. After 500 cycles, the grain-boundary dislocation increment in Ti49Ni46Cu5 was only 108%, compared with 260% in Ti45Ni55, thereby reducing dislocation-mediated fatigue damage. Consistently, the 400 °C-annealed spring delivered the largest actuation stroke of 94.9 ± 5.2 mm, with only 16.6 mm stroke loss after 500 cycles and a low thermomechanical hysteresis temperature of 2.4 °C. This low hysteresis, together with the Cu-induced shift of the middle eigenvalue λ2 toward unity based on the Ball-James theory, reflects reduced associated internal stress and improved transformation reversibility. These results establish a precipitation-assisted dislocation-control mechanism for suppressing functional fatigue in TiNiCu electrothermal actuators.

Understanding the evolution of diffusive hydrogen during mechanical loading is essential for clarifying its role in hydrogen-assisted damage. In this study, a one-way coupled diffusion analysis framework is adopted to model hydrogen desorption during the in situ thermal desorption spectroscopy (TDS)-tensile process. The mechanical response is first established experimentally, and the corresponding stress and strain conditions are treated as fixed inputs to the diffusion problem. The mathematical formulation integrates the theoretical foundations of Sofronis and McMeeking with the McNabb–Foster equation and is numerically implemented using a hybrid Euler scheme. Key characteristics, including lattice hydrogen concentration, trap occupancy distribution, and hydrogen flux evolution, are evaluated. The effects of applied tensile stress, trap type and density, initial occupancy levels, and activation energies are systematically examined. The results reveal that a moderate detrapping energy provides the most effective trapping performance, and the critical threshold at which traps lose their effectiveness is quantified. Furthermore, a fitting procedure is developed that produces physically reasonable parameters while significantly reducing computational cost. This methodology was implemented in the experiment, which enables the determination of optimized trapping and detrapping kinetics from predefined initial conditions and boundary constraints, offering a robust tool for elucidating hydrogen–microstructure interactions.

To simultaneously enhance the strength-plasticity synergy and resistance to hydrogen embrittlement (HE), the post-annealing treatment was conducted in a laser powder-bed fusion Ti-6Al-4V alloy to introduce reversible transformation. The microstructure, mechanical properties, and HE behavior of the alloy were analyzed by electron back-scattered diffraction, transmission electron microscopy, slow-strain-rate tensile test, hydrogen permeation and thermal desorption spectroscopy. The as-printed sample exhibited high strength but limited elongation and high HE sensitivity. When annealed at 550 degrees C, the elongation was improved but the hydrogen diffusion rate also increased, thus promoting the formation of brittle hydride. When annealed at 750 degrees C, the reversible transformation alpha '->beta ->alpha ' occurred and an alpha '/beta/alpha ' sandwich structure formed, thereby enhancing HE resistance (reducing the total elongation loss to 12%) while maintaining high strength (similar to 1116 MPa). The introduction of nanoscale beta-phase and soft-oriented alpha ' grain significantly inhibited hydride formation and hydrogen-induced crack propagation.

Nanoprecipitates typically strengthen alloys by blocking dislocation movement, but herein, they can be sheared off continually during fatigue. Cyclic slip irreversibility accumulates continually, with the local shear strain reaching epsilon(tau) = 57.6 %. We reveal that dislocations slipping on the basal plane experience different critical resolved shear stress (CRSS) as they pass through the beta '-nanoprecipitates. An odd-numbered passing forms an anti-phase boundary (APB) and increases the CRSS, whereas an even-numbered passing removes the APB and reduces the CRSS, following the relationship of tau(2n+1)(a)=tau(2n+2)(a)+2 gamma(APB). Then, as the effective cross-section area of beta '-nanoprecipitates decreases, the CRSS further decreases, following the relationship of tau(n)(a)>tau(n+2)(a). The above gradual softening mechanism of basal slips not only triggers the planar slip behavior, but also promotes fatigue damage localization along those isolated basal planes, which serve as preferential sites for fatigue crack initiation

In this study, the effects of annealing temperature on the recrystallization behavior, deformation modes and mechanical properties of a cold-rolled (CR) metastable Ti-14.7Mo-1.8Al (wt%) alloy were investigated to obtain excellent strength-ductility synergy. At a low annealing temperature of 760 degrees C, the static recrystallization hardly occurs, leading to the lowest tensile elongation (TEL). With increasing temperature to 820 degrees C, the recrystallization process almost completes in a short annealing time of 5 min, contributing to significant grain refinement but preferred orientation of {111}(112) texture component. A high critical resolved shear stress (CRSS) of {323}(131) twinning induces limited twinning-induced plasticity (TWIP) effect and dominated dislocation piling-ups, resulting in localized stress concentration and early fracture. In contrast, a higher annealing temperature of 920 degrees C leads to a higher atomic diffusion rate and growth rate of recrystallized grains with a weakened texture of {001} theta-fiber. The CR-920 sample with a two-stage work hardening possesses the highest TEL without much loss of yield strength (-700 MPa) compared to the CR-820 and CR-760 samples. The excellent tensile ductility can be attributed to the hierarchical activation of dislocation, twinning, martensite and their interactions. The higher Schmid factor (SFR) for dislocation gliding of elemental {001} theta-fiber leads to slip bands formation at low strains. As strain develops, the strong interactions between twins and martensite contribute to sustainable strain hardening, thus postponing the plastic instability.

An intriguing mechanical response was observed in a coarse-grained Ti-10V-4Cr-Al wt.% (TiVCrAl) /1-titanium alloy at room temperature. This alloy accommodates plastic deformation across multiple microstructural scales. The formation of displacive a '/ a '' martensites and the increased activation of high-angle boundaries proved advantageous in the alloy's response to hydrogen, facilitating localized dislocation plasticity and enhancing both strength and ductility. This study combines microstructural characterization with first-principles calculations to reveal key aspects of hydrogen's role in the deformation mechanisms of /1-titanium alloys.