Metals and their compounds are core materials in energy catalysis; however, their performance is often constrained by conventional few-component systems, which typically feature single active sites and limited electronic-structure tunability. These limitations hinder precise regulation of complex reaction pathways and product selectivity. High-entropy strategies offer a promising route to overcome these challenges by enabling multi-element synergistic effects. Nevertheless, introducing multiple elements increases the tendency toward phase separation, making the controllable synthesis of single-phase, compositionally uniform high-entropy materials a key bottleneck for practical applications. To address this issue, this study develops a series of controllable synthesis strategies for high-entropy alloys, high-entropy ceramics, and two-dimensional (2D) high-entropy phosphorus trichalcogenides. Specifically, melt extraction is employed to fabricate high-entropy alloy fibers; pressureless sintering is used to synthesize dense high-entropy metal carbides; solid-state synthesis combined with ultrasonic exfoliation enables the production of 2D high-entropy phosphorus trichalcogenides; and a metal-organic framework-derived strategy is adopted to construct high-entropy metal oxides. These methods enable key advances in high-entropy material synthesis, particularly in compositional homogenization, structural densification, dimensional control, and precursor design. Moreover, the role of high-entropy engineering in regulating catalytic performance is systematically elucidated, highlighting the critical contributions of multicomponent synergy to basal-plane activation, optimization of metal—oxygen covalency, and enhancement of structural stability. Overall, this study aims to provide practical technical pathways and a theoretical framework for developing high-performance high-entropy materials through innovative synthesis strategies and in-depth mechanistic insights.

TC4 titanium alloy is a key material for fabricating load-bearing frame beams in aircraft structures. Narrow gap laser welding offers considerable technical advantages and feasibility for joining thick TC4 titanium alloy plates. However, challenges remain because of substantial variations in the mechanical properties because different regions of the filler layer experience different thermal cycles and heat accumulations. These differences can lead to weak or defective layers, thereby compromising the overall mechanical performance of the weld. Ultrasonic vibration-assisted welding is an effective solution for improving the quality of narrow gap laser welding in thick-walled structures. This study combines the numerical simulations of the temperature and flow fields to investigate the mechanisms of microstructural regulation in different regions of the welded joint, focusing on the effect of ultrasonic vibration on mechanical properties across these areas. The results show that ultrasonic vibration produces a more uniform temperature distribution and increases the fluid flow velocity in the molten pool. Cavitation stress fields and the formation of numerous cavitation bubbles at grain boundaries in the shear direction facilitate grain refinement and promote a more homogeneous grain structure in the weld seam. In addition, the number of needle-like αʹ-martensite structures in the weld zone considerably increases. However, the grain refinement effect gradually weakens from the weld zone to the heat-affected zone. The application of ultrasonic energy improves the microhardness and impact toughness of the filler material layers. Notably, the improvement in the overall mechanical properties of the welded joint gradually declines as the depth from the weld seam increases.

Twin roll casting is a short-process, high-energy-efficiency method for producing aluminum alloy sheets. During the forming process of cast-rolled aluminum alloy sheets, defects such as segregation, coarse secondary phases, and poor properties may occur owing to the quenching effect of the rolling mill rolls. Microalloying can effectively mitigate these defects and enhance the mechanical properties of aluminum alloy sheets produced by cast rolling. In the aluminum alloy twin roll casting process, regulating the recrystallization behavior and improving the microstructure by promoting or suppressing the particle-stimulated nucleation (PSN) effect is critical for producing high-quality cast-rolled sheets. This study prepared six Al-Mg-Si cast-rolled aluminum alloy sheets with varying Zr contents to investigate the evolution of their microstructure and properties, aiming to reveal the influence of Zr content on the recrystallization behavior and mechanical properties of Al-Mg-Si cast-rolled aluminum alloy sheets from the perspective of PSN. The results demonstrated that as the Zr content increased, the grain size initially increased, subsequently decreased, and then increased again. The Zr element was observed to combine with Al to form nano-sized Al₃Zr precipitates with L1₂ structure. These precipitates effectively inhibited the recrystallization behavior associated with PSN in cast-rolled sheets and promoted grain fibrosis. Specifically, when the Zr content was 0.4% (mass fraction), the degree of grain fibrosis reached its maximum; however, with a Zr content of 0.6%, the inhibitory effect of Zr on grain recrystallization was reduced. At this concentration, the coarse D0₂₃-structured Al₃Zr primary phase emerged, exacerbating the PSN effect and increasing the degree of recrystallization in the cast-rolled sheet. Furthermore, as the Zr content increased in the cast-rolled sheet, the size and volume fraction of the Fe-rich phase exhibited a trend of first increasing, then decreasing, and subsequently increasing again. Notably, when the Zr content was 0.3%, the comprehensive mechanical properties of the cast-rolled sheet were optimal. The tensile fracture surface exhibited ductile fracture characteristics, and the Fe-rich phase distribution in the sheet was dispersed. The tensile strength, yield strength, and elongation were measured to be 226.91 MPa, 104.81 MPa, and 15.05%, respectively.

Cu/Al laminated composites combine the lightweight advantage of aluminum with the high electrical and thermal conductivity of copper, and are widely used in the new energy, communication, electric power, and related industries. Traditionally, cold rolling has been the primary method for producing these composites; however, it often results in poor interfacial bonding and promotes the formation of oxides at the interface. In contrast, the high-temperature oxygen-free rolling process can significantly improve composite preparation by enabling precise layer temperature control and creating an anaerobic environment. This process typically forms a mechanical bonding interface, necessitating subsequent annealing to achieve a metallurgical bond that enhances interfacial integrity and optimizes performance. Therefore, developing an annealing process that complements the rolling method is essential. Based on this context, a Cu/1060Al/Cu three-layer composite was fabricated using T2 copper and 1060 aluminum as base materials. The effects of rolling passes and annealing parameters on the mechanical properties and conductivity of the composite were investigated. In addition, the current density distribution within the composite was simulated using Ansys software. After annealing at 350 ^oC for 2 h, the interface layer of the Cu/1060Al/Cu composite became uniform and continuous, with microcracks in the rolled interface layer effectively eliminated. According to strength-plasticity product calculations, the composite exhibited optimal overall performance after two rolling passes, achieving a yield strength of 107 MPa, tensile strength of 178 MPa, and elongation of 67%. Under the combined influence of the interface layer and the constraining effect of the copper layers on both sides of the aluminum core, the composite displayed a collaborative tensile fracture mode. The measured conductivity of the Cu/1060Al/Cu composite reached 70.1%IACS satisfying the requirements for conductor applications. The current density distribution in the annealed Cu/1060Al/Cu composite primarily varied with current frequency, demonstrating the skin effect characteristics typical of alternating current. The current density decreased with increasing frequency and increased with a higher proportion of the copper layer. Notably, increasing the copper layer proportion does not always lead to better performance. It is necessary to comprehensively consider electrical conductivity and material usage when determining the copper layer proportion. An appropriate range for the single-sided copper layer proportion is 10.0%-17.5%.

GH4151 is a heavy alloy, hard-to-deform Ni-based superalloy with service temperatures reaching up to 750-800 ^oC. It is an important candidate material for high-temperature alloys used in the turbine disks of the new-generation advanced aeroengines. During service, the rapid superposition of temperature and stress makes turbine disks susceptible to damage. This study explores the use of hard-to-deform GH4151 alloy used for turbine disks. The tensile behavior of the GH4151 alloy within a temperature range of 23-950 ^oC was investigated using advanced techniques such as SEM, TEM, EDS, and EPMA. The microstructural changes, deformation microstructure, and their impact on the fracture mechanism were analyzed, and the fracture failure mechanisms of the alloy at various temperatures were elucidated. The results indicate that yield strength and tensile strength initially decrease gradually, followed by a rapid decline with increase in experimental temperature. Meanwhile, elongation after fracture of the alloy decreased initially and increased with increasing experimental temperature. The fracture mode transitioned from a mixed fracture to an intergranular fracture. Further research showed that during tensile testing at temperatures of 23-550 ^oC, deformation primarily occurred in the γ channels, with a significant accumulation of dislocations at the γ/γ′ interfaces. This led to the tearing of the γ/γ′ interfaces and the formation of microvoids, which in turn generated a transgranular fracture. The intergranular fracture within the mixed-fracture mode is attributed to the stress concentration at MC carbide interfaces, resulting in the formation of voids. During tensile testing at temperatures of 650-800 ^oC, cracks were initiated via an intergranular fracture, and propagated through mixed-fracture modes. Deformation occurred simultaneously in the γ channels and the γ′ phase. Dislocation pile-up at the grain boundaries accelerated the enrichment of O atoms toward the elastic stress fields or the enrichment of defects at the grain boundaries under high-temperature and high-stress conditions. Such enrichment led to dynamic embrittlement of the grain boundaries, causing intergranular fracture, which reduced the elongation after fracture. As the strain increased, crack propagation was accelerated, reducing the time available for the O atoms to dynamically embrittle the grain boundaries. When the accumulation of dislocations at the γ/γ′ interfaces reached a critical value, crack propagation shifted to a mixed-fracture mode dominated by transgranular fracture. During tensile testing at 950 ^oC, cracks were initiated and propagated via intergranular fracture. The morphology of the γ′ phase changed to an approximately spherical shape, reducing the hindrance to dislocation motion. This reduction did not lead to the coalescence of microvoids at the γ/γ′ interfaces, and thus, no transgranular fracture occurred in the samples tested at 950 ^oC. Because of the decrease in tensile strength at 950 ^oC, the external stress applied was reduced, and crack propagation slowed down, elongation was increased.

Bulk metallic glasses are thermodynamically metastable alloys with an amorphous structure that becomes increasingly unstable at temperatures above their glass transition temperature, leading to degradation of their advantageous properties. Thus, enhancing the thermal stability of bulk metallic glasses is critical for preserving their exceptional characteristics. Recently, our team successfully synthesized a Fe₅₉W₂₃B₁₈ (atomic fraction, %) bulk metallic glass that exhibits high thermal stability and further developed a series of (Fe_{1 - x} Cr _x )₅₉W₂₃B₁₈ (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25) bulk metallic glasses by incorporating Cr in this study. Results show that Cr addition notably enhanced the thermal stability of FeWB bulk metallic glasses, with (Fe_0.9Cr_0.1)₅₉W₂₃B₁₈ achieving a glass transition temperature of 954 K and an crystallization onset temperature of 994 K. This substantial increase in thermal stability is primarily attributed to Cr playing a role in the formation of strong metal-metalloid covalent bonds (Cr—B bonds), which enhance interatomic interactions. Additionally, the substantial presence of an Fe₂₃B₆-like medium-range order structure further stabilized the system. Furthermore, the corrosion resistance of the FeWB bulk metallic glass system was considerably improved by Cr addition, as indicated by an approximately 10-fold reduction in the corrosion current density. This enhancement can be primarily attributed to the formation of a dense Cr₂O₃ passivation layer on the alloy surface. However, the reduced pitting potential of Cr₂O₃ relative to WO₃ led to a slight decrease in the pitting corrosion resistance of the FeCrWB alloys.

Aeroengine bearings, often referred to as the “joints” of the critical aeroengine components, are essential to engine performance, operating under extreme conditions of high temperatures, rapid rotation, and heavy mechanical loads. M50 high-carbon, high-alloy steel, renowned for its exceptional high-temperature stability, hardness, wear resistance, and fatigue resistance, has long been the material of choice for aerospace bearings. Although advances in purification, homogenization, and grain refinement have improved the fatigue life of M50 steel, challenges remain. Notably, microstructural heterogeneities within the matrix, such as coarse carbides, can act as crack initiators under cyclic loading, highlighting the need for advanced microstructural control strategies. This study systematically investigates the evolution of nanoscale carbides in M50 bearing steel during a novel treatment process combining quenching, direct cryogenic treatment, and subsequent tempering, as well as the evolution of residual stress under service conditions. The analyses employed the following methods: small angle neutron scattering and general purpose powder diffraction at the China Spallation Neutron Source, complemented by aberration-corrected high-resolution transmission electron microscopy and residual stress profiling using the contour method. The results demonstrate that elliptical and rod-shaped nanoscale carbides are predominant in the cryogenically treated M50 steel. After tempering, the density of rod-shaped nanoscale carbides increases while the average size decreases, enhancing secondary hardening through the strengthening of carbide dispersion. Remarkably, atomically thin lamellar carbides, with a face-centered cubic structure and bulk enrichment in elements C, Cr, Mo, and V, were identified as precursors to geometrically anisotropic carbides. This novel treatment promotes finer, more uniformly distributed nanoscale carbides comparing to the typical tempering after cryogenically treated microstructure, synergistically improving fatigue strength and hardness while ensuring uniform residual stress distribution in bearing rings. The residual stresses in aeroengine bearing rings under precision and fine grinding conditions are comparable and remain at low levels. Under various service conditions, comparisons between domestically developed and imported bearing rings reveal that after service, transverse residual stress shifts from compressive to tensile, with domestically developed bearings exhibiting residual stress states similar to imported bearings.

In the development of third-generation advanced high-strength steels, achieving a balance between strength and ductility while minimizing alloying and production costs is critical. Among the promising candidates, medium Mn steels (MMnS) have the desired design flexibility for achieving a certain amount of metastable austenite, thereby exhibiting an enhanced transformation-induced plasticity (TRIP) effect. Owing to the weakened alloying effect in low-Mn content MMnS, more efforts should be devoted to enhancing the stability of austenite during intercritical annealing. This study explores the possibility of developing high-strength, high-ductile MMnS via continuous cooling from medium temperatures. A 0.2C-3Mn-1.5Si (mass fraction, %) MMnS was selected to analyze the influence of Mn pre-partitioning on bainite transformation and the volume fraction of retained austenite in low-Mn content MMnS using various characterization methods, including SEM and EBSD, as well as mechanical property testing methods. The results indicate that the carbide-free bainite transformation occurring during the medium-temperature continuous cooling enables the acquisition of retained austenite in MMnS. Mn-rich austenite lamellae can be initially produced via Mn pre-partition during intercritical annealing. Subsequently, bainite transformation is restricted to occur within the undercooled austenite lamellae in the medium-temperature continuous cooling process, resulting in a refined multiphase microstructure comprising film-like retained austenite, bainitic ferrite, and intercritical ferrite. The volume fraction of retained austenite in low-Mn content MMnS substantially increases because of the enrichments of Mn and C from Mn pre-partition and bainite transformation, respectively, thereby enhancing the strength and ductility of MMnS.

Hydrogen embrittlement causes metals exposed to H-containing environments to become brittle and crack, posing serious risks to industries such as energy, manufacturing, transportation, and aerospace. Understanding the interaction between hydrogen and steel is crucial for addressing hydrogen embrittlement challenges. This study uses first-principles methods based on the density functional theory to examine how different alloying elements influence the dissolution of H atoms in α-Fe-based solid solutions, both with and without vacancy defects. The interactions between H atoms and alloying elements, as well as Fe atoms are analyzed using crystal orbital Hamilton populations. Additionally, the climbing image-nudged elastic band (CI-NEB) method was used to calculate the influence of the alloying elements on the diffusion of H atoms in α-Fe-based solid solutions. The results indicate that H atoms preferentially dissolve in the second and third nearest tetrahedral interstitial sites of alloy atoms. The solution enthalpy of H atoms is determined by the bond strength between the H atom and the nearest alloy atom as well as Fe atoms. For systems with vacancy defects after alloying, the solution enthalpies of H atoms at the first nearest vacancy for elements, such as Sc, V, Cr, Mn, Co, Ni, and Cu are lower than those at the tetrahedral interstitial sites of the complete α-Fe-based solid solutions. However, the opposite effect is observed for systems containing Al, Si, Ti, Zr, Nb, Eu, and W. Furthermore, alloying with Ti, Cu, Zr, Nb, and rare-earth elements increases the diffusion energy barriers for H atoms moving from the second nearest tetrahedral interstitial site to the third nearest site, while reducing diffusion energy barriers in the opposite direction. Conversely, the opposite effects are observed in α-Fe-based solid solutions containing Si, V, Cr, Mn, Co, Ni, Mo, and W.

Superalloy ring forgings are a class of prototypical rotary components extensively used in casings, combustion chambers, sealing rings, and support rings in the aviation, aerospace, and nuclear energy fields. These components are often subjected to severe conditions, such as high temperatures, pressures, and rotational speeds as well as the combined effects of high- and low-frequency vibrations. As a result, these ring forgings exhibit excellent mechanical properties and thermal endurance. The microstructure determines the overall mechanical properties of the ring forgings. Their production is complex and involves multiple cycles of thermal deformation. During the thermal deformation phase, the alloy's microstructure undergoes a series of alterations due to the synergistic effects of thermal and mechanical forces. If recrystallization in the preceding stage is incomplete, the resulting microstructure may become heterogeneous and can be carried over to later stages, potentially leading to the formation of mixed crystals. This phenomenon can considerably affect the mechanical performance of ring forgings. Currently, the preparation and formation of ring forgings in China largely rely on traditional “experience-based optimization” approach, which is time-consuming and costly. Therefore, it is essential to establish an accurate microstructural evolution model and predict microstructural changes during thermal processing using numerical simulations. These improvements will enable better control of the alloy microstructure and the optimization of the manufacturing process. To better understand the complex microstructural evolution during the superalloy ring forging formation process, the adaptability of the existing GH4169 alloy microstructure model to the ring rolling process was investigated. Due to the highly nonlinear relationships between the recrystallization kinetics equations and factors such as the strain rate, temperature, and duration of ring rolling, the existing microstructure model was modified. Both the existing and modified models were programmed in FORTRAN language and implemented in Simufact software to simulate microstructural evolution during ring rolling. A numerical simulation method that captures the microstructure inheritance over multiple processing steps was established. The modified model's accuracy and simulation method's feasibility were verified through experiments. A comparative analysis of typical mixed-crystal regions in ring forgings using EBSD and the established numerical simulation, showed that the recrystallized structure of ring forgings combines dynamic and meta-dynamic recrystallization structures. Finally, the established simulation method was employed to analyze the effect of pass deformation on the microstructure during two-pass ring rolling. The results showed that increasing the final rolling deformation improved the uniformity of the ring forgings' microstructure.

The dynamic formation process of microshrinkage pole in alloy castings is directly related to the dendrite solidification process. To simulate dendrite shrinkage in the Al-4.7%Cu (mass fraction) alloy during solidification, we proposed a coupling model combining cellular automata (CA) and the lattice Boltzmann method (LBM), referred to as the CA-LBM model. In this model, CA was used to simulate the formation of shrinkage pores during dendrite growth, whereas LBM was applied to study the diffusion process of shrinkage pores in the liquid phase (fully liquid conditions). First, the accuracy of the proposed CA-LBM numerical model was verified through the numerical simulation of the diffusion homogenization of a vacuum cavity in liquid. Then, the solidification process of a single dendrite—with and without dendrite shrinkage were compared, followed by the calculations of the multi-dendrite solidification contraction process with and without dendrite shrinkage. Simulations of the single-dendrite solidification process indicated that no internal pores were formed in the single dendrites when shrinkage was not considered. However, when shrinkage was considered, uniform microshrinkage pores appeared in the single dendrites. Moreover, the presence of shrinkage pores notably influenced dendrite morphology by promoting secondary branching. The results of the multidendrite contraction simulation also showed that micro-shrinkage pores tended to form at the junctions of the last solidified dendrites. A comparison between the calculated number of shrinkage poles and the theoretical value showed a small error, indicating the effectiveness and reliability of the proposed numerical model.

The grain boundary grooves formed on material surface significantly affect the mechanisms of mass transport, altering the driving force for grain boundary migration, and consequently influencing the kinetics of grain growth. Herein, a phase-field model is developed to simulate the coupled evolution of grain boundary grooving and grain growth in UO₂ ceramic fuels. The process of developing the model begins by constructing a free energy equation for a polycrystalline system, where the reduction in total free energy drives system evolution. The mobility coefficients are then adjusted to ensure that the formation of grain boundary grooves and grain growth follow different kinetic processes. Results show that groove evolution at individual grain boundary is controlled by surface diffusion, aligning closely with Mullins' classical theoretical solution. Moreover, with the movement of grain boundaries, the groove contours become decreasingly symmetric, with increased material accumulation occurring in the grain in front of the moving direction of the grain boundary. The evolution results of a 3D polycrystalline thin film structure show that all grains evolve toward a columnar crystal structure, with grooves gradually forming at the intersections of grain boundaries and the surface. Moreover, grooves generated by different grain boundaries within the same grain tend to overlap on the grain surface, altering the groove contours. With increasing groove depth, grain boundary movement becomes increasingly slow, ultimately reducing the rate of grain growth.

Zn-Pb alloy is an excellent electrochemical material, provided that Pb-rich particles are well dispersed within the Zn-based matrix. When used as the anode in Zn-MnO₂ batteries, the Zn-Pb alloy effectively inhibits hydrogen evolution corrosion, enhances cycling stability, and improves Coulombic efficiency, thus significantly increasing the battery's durability. However, Zn-Pb alloy is a typical monotectic alloy, characterized by liquid-liquid phase transformation during solidification. In this transformation, a homogeneous monotectic alloy melt separates into two liquid phases, resulting in a phase-segregated microstructure that limits the alloy's application. Extensive research has been conducted on the solidification of monotectic alloys. The use of external fields such as ultrasound, electric fields, magnetic fields, and composite electric-magnetic fields to control the solidification structure has been explored. Studies have also investigated the impact of nucleating agents on the solidification process and microstructure. In addition, alloying with a third element to control the solidification process has proven effective. Results indicate that the microstructure evolution during the liquid-liquid phase transition involves complex kinetic behaviors, including nucleation, growth, Ostwald ripening, motion, collision-coagulation of minority phase droplets, and their interaction with the solidification front. The nucleation and migration of minority phase droplets have a dominant influence on the solidification microstructure of monotectic alloys. Adding interface active elements to the alloy melt reduces the liquid/liquid interfacial energy, increasing the nucleation rate and reducing the Marangoni migration velocity of minority phase droplets. This promotes the formation of a well-dispersed microstructure in Zn-Pb alloys. According to the Gibbs isothermal adsorption equation, an element can act as an interface active element if it segregates at the interface between the two liquid phases at the onset of the liquid-liquid phase transition. In this study, solidification experiments were conducted with Zn-4.0%Pb (mass fraction) alloy micro-alloyed with different trace elements to evaluate their effects on the liquid-liquid phase transition. The results indicate that trace elements Sn and In significantly refine Pb-rich particles, while the effects of Cu and Bi are negligible. An analytical model was developed to calculate the segregation behavior of trace elements at the Zn-rich liquid/Pb-rich liquid interface in the Zn-Pb alloy. Calculations reveal that Sn and In segregate to the liquid/liquid interface and act as interface active elements, facilitating effective refinement of Pb-rich particles. In contrast, Cu and Bi cannot act as interface active elements. The segregation behavior of trace elements is closely related to their interactions with Zn and Pb; trace elements can only act as interface active elements if they exhibit weak attraction or repulsion toward both Zn and Pb.