【摘要】 设计出兼具高强度与高塑性的先进金属材料一直是材料领域的永恒研究目标。本文选取CoCrFeNi基面心立方高熵合金作为研究对象，添加原子半径较大的V元素，增大合金的晶格畸变，并通过冷轧加两步退火的热机械工艺在合金中引入晶粒尺寸异质结构，提升合金的强韧性。研究结果表明，这种设计极大地提升了合金的强度，其屈服强度和抗拉极限分别达到了1 059 MPa和1 506 MPa的高应力水平，同时均匀延伸率还维持在21.7%的较高水平。其高的均匀延伸率得益于塑性变形过程中顺序激活了位错、变形孪晶、Lomer-Cottrell锁与层错网的塑性变形机制，有效地提高了合金的加工硬化能力，避免了局部应力集中导致的塑性失稳，从而实现合金的强韧化。更多还原

【Abstract】 Designing advanced metal materials with both high strength and plasticity has been an eternal research goal in the field of materials. In this study, a CoCrFeNi-based face-centered cubic high-entropy alloy was selected as the research object. The V element with a larger atomic radius was added to increase the lattice distortion of the alloy. A grain-size heterogeneous structure was introduced through a thermo-mechanical process involving cold-rolling followed by two-step annealing, aiming to enhance the alloy’s toughness. The results showed that this design greatly enhanced the strength of the alloy, with the yield strength and tensile limit reaching 1 059 MPa and 1 506 MPa, respectively, while maintaining a high uniform elongation of 21.7%. The high uniform elongation was attributed to the sequential activation of various plastic deformation mechanisms, including dislocations, deformation twins, Lomer-Cottrell locks and layer mesh. These mechanisms effectively improved the work-hardening ability of the alloy, preventing plastic instability caused by local stress concentration, thereby achieving the toughening of the alloy.更多还原