Laser welding is widely employed for the aluminum-lithium (Al-Li) alloys owing to the characteristics of low heat input and narrow heat-affected zone. In this work, the laser self-fusion welded joints in AA2195-T6 Al-Li alloy were fabricated under three defocusing amounts (-1 mm, 0 mm, +1 mm). The microstructure evolution, performance and crack propagation behaviour were investigated. The results demonstrate that defocusing amount significantly influences the laser welding quality of Al-Li alloys: Negative defocusing (-1 mm) produces coarse columnar dendrites (22.3 mu m) with high-density defects, resulting in the tensile strength reduction to 230 MPa; whereas zero defocusing (0 mm) promotes grain refinement (11.0 mu m) and increased area fraction (70.1 %) of equiaxed dendrite, improving joint strength to 275 MPa with a weld factor of 47 %. Furthermore, a quantitative relationship between defocusing amount and solidification G/ R ratio was established, elucidating the key mechanism by which defocusing control regulates the transformation from columnar to equiaxed dendrites. It is revealed that TB-(Al7Cu4Li) phase and S-(Al2CuMg) phase induce localized stress concentration through pinning dislocation motion, consequently triggering brittle fracture, which is responsible for the reduction in weld joint elongation. This study provides experimental evidence for optimizing the AA2195-T6 Al-Li alloy welding process and demonstrates that dislocation accumulation serves as a critical mechanism governing brittle fracture in laser-welded joints.

Welded Mg/Al dissimilar metals combine the advantaged performance of aluminum and magnesium alloys, serving as an important application in lightweight structures. It is essential to improve the surface properties of Mg/Al dissimilar metals by adequate treatment due to the galvanic corrosion. In this work, tetraethoxysilane (TEOS) solution was used as the electrolyte for micro-arc oxidation (MAO) of explosive-welded Mg/Al dissimilar metals. The surface morphology, cross-sectional structure, composition, hardness and corrosion resistance of the prepared coatings were characterized by SEM, XRD and electrochemical tests. The results show that by adopting a multi-step MAO treatment in this electrolyte a ceramic coating composed of mainly amorphous silica can be prepared with comparable thickness, hardness and chemical composition on the welded Mg/Al dissimilar metals. The coating grew preferentially on Mg side before 480 V, and at the highest voltage of 520 V the coating on the welded seam and both of Mg and Al sides converged to the thickness of similar to 100 mu m and hardness of 560 HV0.1. After MAO treatment, the corrosion current density of the welded region is three orders of magnitude lower and the impedance is three orders of magnitude higher than the substrate.

Multi-directional forging at 450 °C combined with rolling at 300 °C and 470 °C was applied to a 7050 aluminum alloy prior to heat treatment. The effects of rolling temperature on the microstructure of the alloy were analyzed using optical microscopy, X-ray diffraction, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. After solution treatment, the average grain size of the alloy measured from high-angle grain boundaries was approximately 20 μm, compared to 100 μm before forging. After artificial aging, the yield strength, ultimate tensile strength and elongation after fracture of the samples rolled at 300 °C were (609.9±5.5) MPa, (662.4±1.7) MPa and (18.5±1.2)%, respectively. In the case where the alloy was rolled at 470 °C, the corresponding values were (592.7±4.2) MPa, (641.0±3.9) MPa and (18.7±0.9)%, respectively.

Refractory metals are promising for aerospace and nuclear applications because of their high melting points and stability. However, the processing procedure still encounters challenges due to the high melting point and strong bond strength resulting from the high delocalized electron density of refractory metals. Here we show that liquid metals can dilute this electron density and weaken bond strength, enabling the efficient extraction, dissolution and recombination of refractory metal atoms. This strategy allows the fabrication of bulk refractory materials at notably lower temperatures (<1,000 °C) in a very short time (~2 min). Using this liquid metal-assisted sintering mechanism, we successfully sintered various refractory metal bulks (including W, Re, Ta, Nb, Mo, V, Cr and Ti), achieving equiaxed ultrafine-grained microstructures with excellent yield strength. This mild preparation condition also offers high flexibility for producing alloys, gradient structures and dispersion-strengthened materials, representing an important milestone in developing high-performance refractory structural materials.

Additive manufacturing (AM), as an advanced fabrication technology, is widely regarded as a highly promising approach for the production of TiAl alloys. However, AM-processed TiAl alloys often exhibit microstructural inhomogeneity. In this work, selective electron beam melting (SEBM) was used to fabricate a Ti-45Al-2Mn-2Nb (at%)-0.8vol%TiB2 (45XD) alloy. The as-built 45XD alloy exhibited a uniform and ultrafine duplex microstructure, primarily consisting of alpha 2/gamma lamellar colonies, equiaxed gamma phases, and a small amount of blocky alpha 2 phases. Additionally, rod-like boride particles were observed, being significantly smaller than those in conventional cast alloys. Benefiting from its microstructure, the alloy demonstrated excellent tensile properties and limited anisotropy. At room temperature, although the alloy still has brittleness, its average ultimate tensile strength (UTS) and yield strength (YS) exceeded 800 MPa. When the tensile temperature was elevated to 750 degrees C, the UTS and YS remained above 720 MPa and 620 MPa, respectively, while the corresponding elongation (EL) increased significantly to 7.7 %+/- 2.3. This investigation highlights the application potential of SEBM-built 45XD alloys in high-temperature engineering environments.

In the present work, a eutectic high-entropy alloy (EHEA) consisting of equiaxed C14 Laves and FCC phases was fabricated via hot extrusion of pre-alloyed powders. The compressive behavior of this EHEA was systematically investigated across a wide range of temperatures and strain rates, revealing an exceptional combination of strength and ductility. The multicomponent Laves phase, although intrinsically brittle, exhibits noticeable plasticity under the tested conditions, with cracks initiating in Laves phase and being effectively arrested by the ductile FCC matrix. The FCC phase accommodates strain through dislocation slip, twinning, and dynamic recrystallization (DRX) at elevated temperatures and strain rates, enhancing crack-arresting capability and overall ductility. This work highlights the synergistic role of Laves and FCC phases in achieving balanced strength and ductility, providing a promising design strategy for high-performance structural alloys under extreme service conditions.

Achieving synergy between ultra-high strength and plasticity in nanocrystalline metals remains a grand challenge, as they are typically plagued by intrinsic brittleness arising from catastrophic shear localization. Here, we overcome this limitation by engineering an oxide/nanocrystalline dual-phase (ONDP) architecture within a CoCrFeNiMn high-entropy alloy via rapid current-activated sintering. Guided by atomistic simulations and lattice misfit calculations, a high density of semi-coherent C15-Cr2MnO4 nanoprecipitates was successfully introduced via an ethylene glycol-assisted ball milling and sintering process. The fabricated alloy delivers a compressive yield strength of 4.5 GPa, which is among the highest values reported for nanocrystalline fcc metals/alloys tested by micropillar compression, while maintaining >30% uniform plasticity. Mechanistically, these semi-coherent oxides effectively suppress grain rotation and convert the nanocrystalline matrix into dislocation storage reservoirs, thereby avoiding strain localization and enabling pronounced strain hardening. This study establishes a scalable pathway for stabilizing nanostructures through O-induced dual-phase engineering, offering a blueprint for next-generation high-performance structural materials.

The 2026 aluminum alloy is a damage-tolerant structural material for aerospace applications, where low-cycle fatigue (LCF) resistance is critical to structural safety. In this work, strain-controlled LCF tests with strain amplitudes of 0.6%-0.9% were performed on a 2026 Al alloy in two typical tempers (T4 and T6), and the fatigue behavior was correlated with microstructural evolution. The fatigue life was evaluated using the Coffin-Manson relationship, while an energy-based hysteresis model was employed to extract the intrinsic fatigue damage capacity W0 and the damage-transition exponent beta. The T4 temper exhibits more homogeneous intragranular deformation, assisted by dispersed quenched-in dislocation loops and thermally stable Al3Zr dispersoids, together with the absence of grain-boundary precipitates, leading to a microvoid-dominated damage mode. Consequently, the T4 temper shows high fatigue ductility (epsilon f' = 17.3, c = -1.44) and a higher damage capacity (W0 = 2511 & times; 106 J/m3). In contrast, the T6 temper contains a high density of shearable SI precipitates, which sustain a higher fatigue strength (sigma f' = 1127 MPa) but promote localized cyclic deformation and microcrack-dominated damage with subsurface crack initiation. Within the energy-based framework, the larger beta in the T6 temper indicates a more nonlinear conversion from cyclic hysteresis work to effective damage under localized deformation, consistent with its crack-initiation mode. These results clarify the distinct roles of SI precipitates and intragranular dislocation-loop / Al3Zr features in controlling LCF response, providing guidance for tailoring temper states of Al-Cu-Mg alloys for different fatigue-service scenarios.

The integration of 4J29 Kovar alloy (Fe-29Ni-17Co) and stainless steel can reduce material costs while meeting functional performance requirements in applications such as electronic packaging. In this study, a Kovar alloy/ 304 stainless steel (4J29/304) composite plate was fabricated via explosive welding, and its microstructure and mechanical properties were investigated. An oblique collision welding model was established by smoothed particles hydrodynamics (SPH) algorithm, which reproduced the interface evolution and physical phenomena during plates collision. The results show that the interface between the two materials exhibits a sinusoidal waveform, accompanied by vortices distributed on both sides of individual waves. Equiaxed grains formed through dynamic recrystallisation are observed along the deformed regions adjacent to the interface, while the vortex regions consist of columnar grains and fine equiaxed grains resulting from jet-induced rapid solidification. The microhardness of the flyer plate (4J29) and base plate (304) reach a maximum value near the interface, increasing by 35.3% and 81.9%, respectively, relative to their respective base materials. The shear strength of the 4J29/304 composite exceeds 360 MPa, with shear failure occurring within the 4J29 matrix, indicating excellent interfacial bonding quality.

To clarify the microstructural origin of temper-dependent fatigue crack growth (FCG) resistance in damage-tolerant 2026 Al alloy, the T4 and T6 tempers were investigated using FCG testing, EBSD crack-path analysis, TEM characterization, and fracture-surface observation. Although the T6 temper exhibited higher yield strength and ultimate tensile strength, the T4 temper showed better FCG resistance, including lower crack growth rates in the stable growth region, longer crack-growth life, and higher Kmax before final fracture. At ΔK = 15, 20, and 25 MPa·m1/2, the mean da/dN values of the T4 temper were lower than those of the T6 temper. EBSD results revealed that the T4 temper exhibited stronger crack-path adjustment, larger slip-trace angle fluctuations, higher crack-path grain orientation spread (GOS) ratio, and a higher grain-crossing deflection probability than the T6 temper. The overall deflection probability was 73.3% for T4 and 45.0% for T6. TEM observations further showed stronger local dislocation accumulation and Al3Zr-related strain contrast in the T4 temper, whereas the T6 temper showed SⅠ precipitate-constrained localized plasticity, locally observed GBP/PFZ features, and localized dislocation pile-up/cutting. The superior FCG resistance of the T4 temper is associated with greater dislocation accumulation during crack growth, larger crack-tip cyclic plasticity, and more frequent crack-path adjustment rather than tensile strength alone.

Laser welding of AA2195-T6 Al-Li alloy is conventionally optimised based on heat input H = P/V. However, this parameter overlooks the independent roles of laser power and welding speed. This study elucidates the synergistic effect of power and speed under constant heat input. Three power-speed combinations (2300 W 3.5 m/ min, 2600 W 4.0 m/min, and 2900 W 4.5 m/min) at 39 +/- 1 kJ/m were investigated. Results show that high power-speed synergy (2900 W 4.5 m/min) refines the microstructure, narrows the heat-affected zone, and simultaneously enhances tensile strength (265 MPa) and corrosion resistance (depth reduced from 85.2 to 59.2 mu m). These findings demonstrate that power-speed synergy, rather than heat input alone, governs weld performance.

This study investigated the compressive creep behavior of a selective electron beam melted (SEBM) Ti-48Al-2Cr2Nb alloy under various applied stresses at temperatures ranging from 750 degrees C to 850 degrees C. The microstructural evolution under high-temperature and high-stress conditions was analyzed. The creep stress exponent (n) varied between 4.5 and 6.1, with an activation energy (Qc) of 427.0 kJ/mol at 200 MPa, suggesting the creep mechanism was dominated diffusion-assisted dislocation motion. Microstructural observations further revealed that creep deformation was primarily governed by dislocation climb, deformation twins and their interactions. Owing to the alloy's layered heterogeneous microstructure consisting of alternating coarse-grained (CG) and finegrained (FG) regions, scale-dependent twinning behavior was observed: wide deformation twins were frequently observed in CG regions, while nanotwins formed preferentially in FG regions. At 850 degrees C, extensive dynamic recrystallization (DRX) occurred, predominantly via discontinuous DRX (DDRX); continuous DRX (CDRX) was activated with increasing creep strain. The initial deformation at 850 degrees C/200 MPa was accommodated by dislocation pile-ups, deformation twins, and stacking faults, which were subsequently replaced by DRX grains during prolonged exposure. These findings provide a comprehensive understanding of compressive creep in additively manufactured TiAl alloys.

The thermo-mechanical processing of CoCrNi medium-entropy alloy was investigated by comparing two distinct routes: direct hot rolling (HR) and hot-plus-cold rolling (HCR), designed to produce initial states with low and high stored energy, respectively. The HR process yielded a thermally stable microstructure with low initial stored energy, retaining hardness and strength up to 700 degrees C. This stability is underpinned by sustained TwinningInduced Plasticity (TWIP) activity across all tested conditions. Conversely, the high-stored-energy HCR alloy displayed a complex, non-monotonic annealing response. An anomalous strengthening effect was observed upon annealing at 550 degrees C, accompanied by a severe loss of ductility and work-hardening capacity. This behavior is attributed to recovery-induced strengthening, originating from local chemical composition fluctuations (specifically atomic clustering) at the high density of crystal defects introduced by cold rolling. This atomic clustering effectively pins the deformation substructure, inhibiting twinning and promoting a transition to localized planar slip and premature failure. At higher temperatures (>= 650 degrees C), extensive recrystallization eliminates the dense defect substructures, thereby "rejuvenating" the TWIP effect and restoring ductility. This study clarifies the competition between recovery-induced strengthening (mediated by atomic clustering), recrystallization, and the TWIP effect, demonstrating that controlling initial stored energy via direct hot rolling is a promising strategy for designing thermally stable alloys.

As a key material for aero-engine blades, the high-temperature creep resistance of TiAl alloys is of critical importance. Although hot isostatic pressing (HIP) is widely employed to eliminate defects in additively manufactured (AM) components, its influence on this key property is still insufficiently understood. In this work, a Ti48Al-2Cr-2Nb alloy fabricated via selective electron beam melting (SEBM) technology was subjected to HIP treatment to investigate its effects on microstructure, high-temperature tensile properties, and creep resistance. The results reveal that the as-built TiAl alloy exhibits a heterogeneous microstructure, comprising coarse gamma-phase regions and fine duplex regions (consisting of gamma phase and lamellar alpha 2/gamma). After HIP treatment, the heterogeneous microstructure remains present, but with slightly coarser grains and a reduced dislocation density, resulting in reduced high-temperature tensile strength and improved ductility. Furthermore, the complete dissolution of lamellar structures and the growth of the alpha 2 phase in the fine-grained regions led to a deterioration in hightemperature creep resistance. Nevertheless, the underlying creep mechanism remains unchanged, with dislocation creep still being the dominant deformation mechanism. The work highlights the critical trade-offs imposed by HIP and provides valuable insights for optimizing post-processing for AM TiAl components in hightemperature applications.

Nanovoids were generated in Al-Cu-Sn via the addition of a heating step between solution treatment and ageing. After ageing for 1 h at 200°C, the yield strength of the alloy increased by 11.2% compared to the case where it was not subjected to this heating step, while the elongation at break remained similar. Transmission electron microscopy (TEM) characterisation was performed to understand the nature of the strengthening brought by the additional heating (AH) and the strength contribution of the nanovoids. It is revealed that the alloy contained approximately one void per 50 μm−3 on average, all with mean dimensions of tens of nanometres. The number density of strengthening precipitates in the alloy subjected to AH was three times that of the case where it was not subjected to this heating step. Through calculation, we found that the presence of the voids in these samples contributed to a decrease of ∼20 MPa in yield strength. The stability of the voids during prolonged ageing was also investigated. This work provides useful insights into tuning nanostructures for the desired mechanical properties of aluminium alloys.

Achieving ultrahigh wear-resistance in structural coatings requires integrating high intrinsic strength with the ability to sustain plastic deformation. Here, we report a dual-phase nanocrystalline FeCoNiTi multiprincipal element alloy (MPEA) coating that attains a high yield strength of 3.3 GPa, a strain-hardening rate of 9.21 GPa, and an ultralow wear rate of 1.1 × 10-6 mm3/(N·m), surpassing most reported MPEA coatings. The coating is synthesized via rapid electrical-current-activated sintering, during which amorphized FeCoNiTi powders crystallize into a uniform fine-grained FCC matrix (∼32.5 nm) with ∼40 vol % ordered coherent L12 nanoprecipitates. Addition of Ti promotes compositional segregation and L12 phase formation, which facilitates twinning-induced plasticity and enhances strain hardening. The in situ formation of a TiO2 tribo-film also provides a lubrication effect. Furthermore, the twin-mediated deformation suppresses strain localization and grain boundary sliding. This work establishes a rapid and robust pathway for designing high-performance antiwear coatings through alloying-driven phase selection and defect engineering.

This study explores the fabrication of crack-free TA15/TiAl bimetallic structures prepared by laser directed energy deposition (LDED) for high-temperature applications. By employing laser power (800-1600 W) for S1-S5 (1600, 1400, 1200, 1000, 800 W, respectively), defect-free interfaces were achieved, with sample S2 (1400 W) exhibiting the lowest porosity (0.19 %) and finest microstructure. The transition zone exhibited a composition gradient of Al/Ti, driven by atomic diffusion and Marangoni convection, resulting in a heterogeneous multi-gradient structure. Notably, the uniform distribution of FCC phase in the transition zone reduced stress concentration from Al3Ti hard phase, while the absence of cracks and lack-of-fusion defects confirmed robust metallurgical bonding. Room-temperature tensile tests showed that sample S2 fractured near the TiAl side, achieving an ultimate tensile strength of 780 f 25 MPa and elongation of 1.41 f 0.11 %, attributed to stress redistribution facilitated by ductile alpha-Ti and gradient strain accommodation. These findings demonstrated that LDED-fabricated TA15/TiAl bimetallic composites exhibited enhanced interfacial strength and thermal stability, promising for aerospace components in extreme environments.

In this study, a CoCrNi/316L composite is prepared via explosive welding. The interface of the CoCrNi/316L composite exhibits a uniform wavy structure with vortices. The formation mechanism of the wavy interface is clarified using smoothed particles hydrodynamics (SPH) simulation, which is also employed to calculate the temperature and strain distribution at the interface during the explosive welding. By correlating the simulated temperature and strain fields at different locations with the experimentally observed grain characteristics, the formation mechanism of various grain types near the interface is analyzed. The CoCrNi matrix consists of ultrafine equiaxed grains formed through dynamic recrystallization (DRX), while the 316L contains coarse grains characterized by high stress due to severe deformation. The vortex zones are primarily composed of columnar grains resulting from crystallization of molten liquid. Nanoindentation test results show that the hardness progressively increases from the matrix to the interface. Notably, the interfacial shearing strength of the CoCrNi/316L composite reaches up to 796 MPa.

Cubic perovskite-Ti3AlC carbides are essential strengthening particles in TiAl alloys, especially for application above 800 degrees C where coarsening is expected to occur. However, these carbides can decompose into small subparticles upon extended annealing, and the underlying atomic-scale mechanisms, especially structural and compositional changes, driving this unique splitting remain unclear. This study revisits this behavior in a Ti45Al-5Nb-0.75C alloy utilizing probe-corrected transmission electron microscopy, atom probe tomography and first-principle calculations. The results reveal that the elastic interactions significantly influence carbide evolution. While needle-like carbides transform to intact plates during aging, those in high-density regions tend to coalesce or align along elastically softest gamma-matrix directions, forming low-energy plate-like carbide conglomerates. With extended annealing, periodic chemical fluctuations driven by lattice misfit, especially along the needles induce splitting. Simultaneously, a gamma i-phase with a larger tetragonality and a 90 degrees-rotated c-axis relative to the gamma matrix emerges between the sub-particles, which exhibits near-zero lattice mismatch with carbides along [001], combined with mass-center shifts of carbides, further stabilizing the split configurations. This study provides atomic-scale insights into the evolution and stability of strengthening precipitates in systems with tetragonal misfit, and offers new strategies for improving creep properties of TiAl alloys by tailoring carbide configurations.

The search for highly efficient, low-priced and well-stabilized bifunctional oxygen catalysts is the current research focus of Zinc Air Batteries (ZABs). In this paper, PtFeCoNiMoY high-entropy alloy (HEA) nanoparticles are successfully coated on carbon nanotubes (CNTs) using a simple one-step gas-phase synthesis. The catalyst exhibits outstanding performance with an OER (oxygen evolution reaction) overpotential of 238 mV (10 mA cm- 2 ) and a bifunctional oxygen overpotential (Delta E) of only 0.713 V. In addition, the catalyst shows better performance when used as a cathode for ZABs, with a high specific capacity (797 mA h/g), peak power density (128.4 mA cm- 2 ) and long-term cycling stability of more than 80 h. XPS results show that the addition of Mo and Y elements can result in a change in the electronic structure of the alloy. DFT (Density functional theory) calculations point out that the addition of Mo elements makes the alloy's upper-spin state electrons more continuous near the Fermi energy level. The addition of Y elements shifts the overall d-band center of the alloy downward, which serves to regulate the surface adsorption energy. The work in this paper will promote the study of Pt-based bifunctional electrocatalysts and their practical application in ZABs.