The development of high-entropy alloys with ultrahigh compressive strength and retained limited deformability is of considerable interest for load-bearing applications under compression-dominated service conditions. This work investigates the effects of Ti/Nb co-alloying on the microstructure and compressive behavior of CoCrFeNi (TixNb1-x) HEAs, where x is the molar ratio and equals 0, 0.25, 0.5, 0.75, and 1. Increasing Ti content promotes the formation of a hard Laves phase and significant grain refinement, resulting in an increase in Vickers hardness from 142.2 HV to 855.5 HV. Under compression, CoCrFeNi(Ti0.5Nb0.5) exhibits the highest load-bearing capability, with a yield strength of 1979.6 MPa and a fracture strength of 1988.1 MPa, while retaining a limited but measurable fracture strain of 6.5%. Microstructural analysis using XRD, SEM, EBSD, and TEM reveals that this alloy derives its ultrahigh compressive strength from a ceramic-like microstructure consisting of a dispersed Laves phase, a continuous FCC matrix, and refined grains. EBSD-KAM analysis indicates that strain partitioning between the phases enhances dislocation accumulation, thereby contributing to strengthening. In contrast, excessive Ti promotes the formation of a continuous Laves-phase network, which facilitates premature cracking and brittle failure. These findings demonstrate that Ti/Nb co-alloying enables a "ceramic-like" strengthening mechanism by regulating the Laves-phase architecture, offering a practical microstructural design strategy for developing CoCrFeNi-based high-entropy alloys with ultrahigh compressive load-bearing capability while avoiding fully brittle failure.

Dual-phase BCC refractory high-entropy alloys (RHEAs) have emerged as promising candidates for advanced structural materials due to their high strength and phase stability derived from their refractory nature. Here, the influence of quenching temperature on phase constitution, microstructural evolution, and room-temperature mechanical behavior of (Ti25Zr25Nb20Hf5Ta15W10)100-xYx (x = 0.1-0.5 at%) RHEAs is systematically investigated. Increasing the quenching temperature markedly promotes the solubility of Y in the BCC matrix, leading to pronounced microstructural refinement. By increasing the quenching temperature, the solubility of Y elements in the BCC matrix is significantly enhanced, thereby promoting solid solution strengthening and grain refinement mechanisms. Under moderate Y content conditions, the synergistic effects of solid solution strengthening and grain refinement markedly optimize the microstructure, leading to a significant improvement in the alloy's compressive plastic deformation capacity and fracture toughness. Notably, the alloy containing 0.2 at% Y shows the optimal mechanical performance: the as-cast alloy achieves a compressive plastic strain of 21.5 % and a toughness of 321 MJ m-3, while quenching at 1000 degrees C further increases the plastic strain to 35.5 % and the compressive toughness to 484 MJ m-3 without a significant loss in strength. These results demonstrate that controlled rare-earth alloying combined with thermal processing provides an effective strategy for tailoring the strength-ductility balance of dual-phase RHEAs, offering new insights into the design of high-toughness refractory alloys for structural applications.

This study systematically investigated the microstructure and mechanical properties of SiC-induced multiphaseregulated high-entropy alloys (SIM-HEAs) with the composition Al0.25CoCrFeNiV0.35(SiC)x (where x = 0, 0.05, 0.1, 0.15, 0.2 at%). Microstructural characterizations indicated that the introduced SiC predominantly underwent reactive decomposition during the high-temperature melting process. The released C atoms reacted with elements such as V and Cr in the alloy, leading to the sequential formation of VC and M7C3 phases. As a result, the alloy gradually evolved from its original face-centered cubic (FCC) + sigma phase structure into a multi-phase structure consisting of FCC, sigma, VC, and M7C3. A small amount of SiC remained dispersed in the matrix. Mechanical testing results showed that the addition of SiC significantly modulated the mechanical properties, increasing the alloy's tensile strength from 634.2 MPa to 929.9 MPa, while allowing for a tailored balance between strength and ductility. The alloy with 0.1 at% SiC exhibited a good balance of strength and ductility, while the alloy with 0.2 at% SiC demonstrated the highest yield strength, although at the expense of some ductility. Analysis of the strengthening mechanisms indicated that the improvement in the alloy's mechanical properties was primarily due to the evolution of the multiphase microstructure and the combined effects of strengthening mechanisms, such as dislocation strengthening, Orowan strengthening, and grain boundary strengthening maintained by carbide pinning.

Achieving a favorable balance among strength, ductility, and damage tolerance remains a key challenge for CoCrFeNi-based FCC high-entropy alloys. Here, a series of (CoCrFeNi)98.65C0.15TixNb1.2-x alloys with varying Ti/Nb ratios were designed to reveal the role of Ti–Nb–C microalloying in controlling as-cast microstructure and mechanical response. The Ti/Nb ratio strongly influenced the as-cast grain structure, local KAM distribution, and tensile properties. Among them, (CoCrFeNi)98.65C0.15Ti0.6Nb0.6 exhibited the optimal as-cast strength–ductility combination, with an ultimate tensile strength of 628.8 MPa, fracture strain of 52.7%, and static toughness of 270.3 MJ m−3. Using this optimized composition, conventional cold rolling–annealing and deep cryogenic treatment–annealing routes were compared. After annealing at 700 °C, the DCT-assisted alloy (HCRDA700) achieved an ultimate tensile strength of 992.9 MPa, a fracture strain of 23.7%, and static toughness of 240.3 MJ m−3. Microstructural analyses indicate that this superior performance arises from the synergistic effects of fine recrystallized FCC grains, annealing twins, residual substructures, inherited stacking-fault/twin-related features, and thermally stable nanoscale (Ti,Nb)C carbides. Deep cryogenic treatment at 77 K does not directly drive diffusion-controlled precipitation, but stabilizes defects and local strain, thereby regulating subsequent recrystallization and carbide formation during annealing. These results demonstrate an effective strategy for optimizing FCC high-entropy alloys through coupled Ti/Nb ratio design and deep cryogenic treatment–annealing, enabling a simultaneous improvement in strength, ductility, and damage tolerance.

Al0.25CoCrFeNi(SiC)0.1Vx (x = 0.05, 0.15, and 0.25) high-entropy alloys were fabricated by vacuum arc melting and evaluated in 3.5 wt.% NaCl solution to clarify the relationships among V content, carbide evolution, electrochemical response, and localized corrosion. Potentiodynamic polarization and electrochemical impedance spectroscopy were combined with microstructural, surface-chemical, and local-potential analyses. All alloys consisted predominantly of an FCC matrix and Cr/V-enriched M7C3-type carbides, with no distinct residual SiC phase. Increasing V content promoted V partitioning into the M7C3-type carbides and increased their area fraction. Correspondingly, the corrosion current density increased from 0.573 to 2.163 μA cm-2, while the charge-transfer resistance decreased, accompanied by increasingly severe localized corrosion adjacent to the carbides. The V0.05 alloy was subsequently cold rolled and annealed at 700–900°C. Thermomechanical processing produced a non-monotonic electrochemical response, with AN900-V0.05 exhibiting the lowest corrosion current density and the greatest resistance to interfacial charge transfer. Its improved corrosion behavior was associated with grain refinement and recrystallization, carbide redistribution, reduced carbide/FCC Volta-potential contrast, and a more highly oxidized surface film. These results link V-content-dependent carbide evolution with localized-corrosion susceptibility and demonstrate that thermomechanical processing can mitigate local electrochemical heterogeneity and suppress interfacial charge transfer.

This work systematically investigates the effects of trace Gd addition and thermomechanical processing on the corrosion behavior of CoCrFeNiV0.4 high-entropy alloy in 3.5 wt.% NaCl solution. The corrosion resistance first increases and then decreases with increasing Gd content, with Gd0.01 being the optimal composition. Cold rolling promotes passivation, while subsequent annealing further improves corrosion resistance through recrystallization and microstructural homogenization; the Gd0.01 sample annealed at 850°C (Gd0.01CR850) exhibits the best performance, with a corrosion current density as low as 1.68 × 10-5 A/cm2 and a charge-transfer resistance as high as 2.41 × 105 Ω·cm2. EBSD analysis reveals that trace Gd refines grains and promotes recrystallization, effectively reducing residual strain and the density of electrochemically active sites. XPS analysis further demonstrates that the optimal passive film incorporates Gd2O3, with increased fractions of V2O5 and NiO and reduced hydroxide content, significantly enhancing film chemical stability. The synergistic effect of microstructural homogenization and passive-film chemistry optimization is the fundamental reason for the improved corrosion resistance. This work provides experimental guidance for the microstructural and interfacial design of corrosion-resistant CoCrFeNiV-based HEAs for marine and other chloride-containing environments.

This study fabricated the Al-Y sol-gel film on a GH4169 superalloy substrate using the sol-gel method. Cyclic oxidation tests at 950 °C were conducted to evaluate the influence of composite sol coatings with different Al/Y ratios on the alloy’s high-temperature oxidation resistance. The addition of a trace amount of Y enhanced both the oxidation resistance and spallation resistance of the alloy by forming a Y3Al5O12 (YAG) diffusion barrier, which promoted the selective oxidation of chromium, resulting in a synergistic protective effect. However, excessive Y content leads to defects such as voids and cracks within the oxide layer, increasing oxidation weight gain. Further analysis of the oxide layer on the Al-Y sol-gel coated specimen revealed a three-layer structure: the outer Cr2O3 phase, the intermediate Y3Al5O12 diffusion barrier, and the inner Nb2O5 layer.

This study systematically investigated the microstructural evolution and mechanical properties of carbide-reinforced CoCrFeNi-based high-entropy alloys through the synergistic regulation of carbon addition and the Ti/Zr ratio. The results show that the introduction of Ti, Zr, and C promotes the in-situ formation of titanium/zirconium-containing carbides and Laves phases, while the Ti/Zr ratio effectively tailors the carbide composition and the competitive precipitation behavior of these two secondary phases. As the Ti content increases, the hardness, yield strength, and compressive strength increase continuously, while the fracture strain also shows an increasing trend. Among the investigated alloys, the alloy with an equiatomic Ti/Zr ratio exhibits a fracture strain of 22.7

Refractory high-entropy alloys (RHEAs) are a promising class of materials with excellent mechanical properties, making them potential candidates for advanced structural applications. In this study, a novel series of (Ti25Zr25Nb20Hf5Ta15W10)100-xYx was designed and systematically investigated to understand the influence of Y addition on their microstructure, phase evolution, and mechanical performance. The alloys exhibit a dual-phase BCC (major and minor) structure, with the relative phase fractions and grain morphology strongly affected by Y content. Comprehensive microstructural analyses reveal that Y induces grain boundary segregation and promotes grain growth, accompanied by changes in grain orientation and boundary behavior. At an optimal Y content of 0.2 at.%, the alloy achieves a balanced combination of strength and ductility, with a yield strength of 1838.7 MPa and a fracture strain of 19.8 %. This is attributed to a synergy of solid solution strengthening, grain boundary reinforcement, and dislocation motion regulation. Furthermore, Y addition enhances grain boundary sliding and promotes plastic deformation, providing insights into the role of rare-earth elements in optimizing mechanical properties. This work provides a comprehensive understanding of Y-induced microstructural and mechanical evolution in refractory HEAs, offering theoretical and experimental guidance for designing next-generation high-performance alloys.

Dual-phase body-centered cubic (BCC) refractory high-entropy alloys (RHEAs) are promising candidates for advanced structural applications due to their exceptional mechanical properties. In this study, Ti25Zr25Nb20Hf5Ta15W10 RHEAs were fabricated using vacuum arc melting, and the effects of quenching temperatures (800 degrees C, 1000 degrees C, and 1200 degrees C) on the microstructure and mechanical properties were investigated. The results demonstrate that both as-cast and quenched alloys maintain a dual-phase BCC structure with remarkable high-temperature stability. Room-temperature compression tests reveal that the as-cast alloy has a yield strength of 1264 MPa, compressive strength of 1889 MPa, and fracture strain of 27.7 %. After quenching at 1200 degrees C, the yield strength increases to 1468 MPa, compressive strength to 2117 MPa, and fracture strain to 33.5 %. These enhancements are attributed to the synergistic effects of solid solution strengthening and morphological refinement of dendrites: the atomic size mismatch between W and Hf induces significant lattice distortion, while the equiaxed grain structure resulting from dendrite selective dissolution contributes further grain refinement strengthening. This dual strengthening mechanism activates both dislocation strengthening and microstructural strengthening, resulting in an outstanding balance between strength and ductility. This study provides valuable insights into the effects of quenching on RHEAs, offering guidance for the development of high-performance alloys.

This study investigates the effects of rare earth erbium (Er) modification and annealing treatment on the microstructure, mechanical properties, and electrical conductivity of 8030 aluminum alloy. The alloy’s microstructure was analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron backscatter diffraction (EBSD). Hardness, tensile strength, and electrical conductivity were measured to evaluate the mechanical properties and performance of the alloy. The results indicated that the addition of Er reduced the size of the Al3Fe phase, and transformed its typical elongated, claw-like morphology into a more spherical shape. Furthermore, the L12-structured Al3Er phase preferentially nucleated at the liquid-solid interface, forming globular particles that impeded the growth of both α-Al and Al3Fe phases. With the addition of 0.35 wt.

This study systematically investigates the effects of trace Gd addition on the microstructural evolution and mechanical properties of GdxCoCrFeNiV0.4 high-entropy alloys with varying Gd concentrations (x = 0, 0.01, 0.03, and 0.05). The results show that the Gd0.01CoCrFeNiV0.4 alloy does not exhibit any hexagonal structure (HS) phase, in contrast to higher Gd contents. Cold rolling and annealing treatments were applied to both Gd0.01CoCrFeNiV0.4 and CoCrFeNiV0.4 alloys. While the base CoCrFeNiV0.4 alloy remained in a single facecentered cubic phase, the Gd-doped alloy developed Gd-rich precipitates. Notably, the Gd0.01CoCrFeNiV0.4 alloy exhibited improved tensile properties, with a yield strength of 378 MPa, ultimate tensile strength of 809 MPa, and elongation to failure of 45 %, after 850 degrees C annealing. The enhancements were attributed to the combined effects of solid solution strengthening, grain refinement, and the synergistic contributions of dislocations, stacking faults, annealing twins, and nanotwins. Minor Gd-rich precipitates also contributed positively to the alloy's mechanical performance, especially in terms of toughness. These findings provide valuable insights into the design of high-performance HEAs with trace element additions.

In this study, the effects of the addition amounts of rare earth element Ce (0, 0.2, 0.4, and 0.6wt.

The grain boundary characteristics of different microcomponents of isomeric aluminum alloys determine their properties, but the grain boundary evolution and deformation mechanism of multi-scale grains need to be further clarified.In this paper, the Al-Cu-Mg alloys sheet was fabricated by sintering of coarse and fine particle size powder and hot extrusion. The results show that when the proportion of coarse powder is 30 % and 50 % respectively, the special structure of elongated coarse crystal band and fine crystal distribution will be formed after hot extrusion, and it shows excellent mechanical properties.Among the three groups of samples, the sample with 30 % coarse powder (CG30) exhibits the highest ultimate tensile strength at 340.23 MPa, representing a 19.58 % increase in tensile strength compared to the sheet prepared using pure fine powder. This enhancement can primarily be attributed to the reduction in the texture intensity of the < 110 > oriented texture of coarse crystals, thereby eliminating the pronounced preferred orientation of grains and mitigating localized stress concentration. The sample with 50 % coarse powder (CG50) showed the best elongation, reaching 27.50 %, which was increased by 32.79 % compared with CG0. The high grain boundary energy storage of the heterogeneous structure promoted the opening of the OC slip system, and the stable grain direction avoided the local softening or hardening caused by the preferred orientation, and the material elongation was improved. The incorporation of coarse powder enhances the misorientation at the grain boundaries and alters the stress distribution within these regions and affects the opening of different slip modes and the change of texture strength, which helps to improve the mechanical properties of heterogeneous aluminum alloy sheet and provides a new idea for the forming and manufacturing of high-performance heterogeneous Al-Cu-Mg alloys sheet.

This study investigates the synergistic effects of Gd microalloying (0.01 at.%) and thermomechanical processing (50 % cold-rolling, 1123 K annealing) on the cryogenic performance of CoCrFeNiV0.4 alloys. The Gd0.01CR850 alloy exhibits superior strength (1055.5 MPa) and ductility (55.7 %) at 77 K, demonstrating a successful balance between strength and toughness at low temperatures.

Given the limitations of traditional hot extrusion methods in improving the microstructure and mechanical properties of magnesium(Mg) alloys, this paper attempts to treat AZ31 Mg alloy billet by pre-upsetting continuous variable cross-section direct extrusion (U-CVCDE). The effects of dynamic recrystallization behavior and slip system activity on texture evolution and mechanical properties of CVCDE Mg alloys with different pre-upsetting amounts were systematically analyzed. The results indicate that the introduction of the pre-upsetting process promotes dynamic recrystallization during the CVCDE process. The recrystallization proportion shows a trend of first rising and then decreasing with the increase of the pre-upsetting amount. Among them, the proportion of recrystallization grains in the U2-CVCDE-formed structural parts is as high as 88.3%. The average grain sizes of U1-CVCDE, U2-CVCDE, and U3-CVCDE were 6.01 µm, 4.90 µm, and 10.45 µm, respectively. In addition, following U-CVCDE, the pyramidal slip of each forming component consistently maintains a high level of activation and opening and dominates, making more grains deflect in the axial extrusion direction of C to varying degrees, which is conducive to the uniform distribution of stress in more grains during plastic deformation. The synergistic effect of dynamic recrystallization behavior and the high activity of the pyramidal slip system significantly weakened the (0001) basal texture strength, and the maximum basal texture strength showed a gradually decreasing trend, among which the base surface texture strength of U3-CVCDE formed parts was only 9.9. The U-CVCDE process is employed to achieve deep modification of Mg alloy, and excellent comprehensive mechanical properties are obtained; among them, the yield and tensile strength of U2-CVCDE are as high as 243.4 MPa and 317.5 MPa, respectively, and the elongation after breaking is up to 21.3%. This study introduces a practical new idea for investigating the extrusion forming technology of high-performance Mg alloys.

Novel Ti/Al laminated composite embedded with particles of the high entropy alloy Al0.5CoCrFeNi were produced by vacuum hot press sintering at 650 & DEG;C. The microstructure of the laminated composite was investigated using XRD, SEM, EDS, TEM and EBSD techniques. It was found that a thin layer of Al3Ti was formed at the Ti/Al interface. There were no obvious defects between the Al0.5CoCrFeNi particles and Al matrix, achieving a good interfacial bond. The tensile properties of the material were tested at room temperature. The results of the tensile test indicated that the material exhibited an elongation to failure of 59% and an average tensile strength of 240 MPa, demonstrating excellent plastic deformation capability. During the tensile process, the expansion of fractures and cracks in Al0.5CoCrFeNi particles can consume energy, which helps to improve the material's ability to undergo plastic deformation. Based on the morphologies of tensile fracture, it has been observed that the fracture surface of high entropy alloys exhibits a mixed fracture mode consisting of both brittle and plastic fracture. The brittle BCC phase has been identified as the main cause of cracking in HEA. Ultimately, the material fractures due to necking.

In this study, the microstructure and mechanical properties of Al0.45CoCrFeNiTix (x = 0, 0.25, 0.5, 0.75, 1.0) high-entropy alloys were investigated. Various techniques including XRD, SEM, EBSD, and TEM were employed, along with hardness tests, compressive tests, and tensile tests conducted at room temperature. Our findings reveal that the alloy's microstructure changes from FCC + BCC to FCC + BCC + L21 phase as the Ti content increases. Specifically, the BCC content increases from 0.9 % to 62.3 %. This alteration in microstructure leads to a significant enhancement in the compressive yield strength of the alloy, from 305.96 MPa to 1492.53 MPa. The observed strengthening effect can be attributed to the increased BCC content and the formation of the L21 phase within the alloy. The results of the tensile experiments demonstrate that the Ti0.25 alloy exhibits the most favorable overall properties, possessing a yield strength of 619 MPa. This represents a significant increase of 64.6 % when compared to Ti0. The strengthening mechanism of the Al0.45CoCrFeNiTix high-entropy alloy is thoroughly discussed. The main strengthening mechanisms of the alloy system are fine grain strengthening, solid solution strengthening and second phase strengthening. This study achieves a balance between strength and ductility by modulating the phase composition of the alloy, laying the foundation for further development and research into the properties of the high-entropy alloys.

The effects of Cu addition (0.01, 0.1, 0.5 and 1 wt.

This study focused on examining the impact of heat treatment on the microstructure, mechanical properties, and corrosion resistance of 2024 aluminum alloy. Various techniques such as OM, XRD, SEM, and TEM were employed for microstructural characterization. The findings revealed that subjecting the alloy to a homogenization process at 493 °C for 18 h led to significant improvement in alloy organization, dissolution of coarse second phase, and enhanced machining and deformation capabilities. Additionally, two-stage aging resulted in a more uniform distribution of precipitated phases, increased density, and the predominant precipitated phase being the reinforced phase S phase (Al2CuMg). The hardness test and tensile test were conducted, revealing that the alloy achieved 142.1 HV in hardness, 494.4 MPa in tensile strength, and 19.7