Abstract In this study, nonequiatomic Co28.5Cr21.5Fe20Ni26Mo4 medium-entropy alloys (MEAs) were prepared using hot isostatic pressing. The effect of annealing heat treatment on microstructure and mechanical properties of MEAs was investigated. The results showed that the microstructure of as-sintered alloys was mainly composed of the face-centered cubic (FCC) phase and μ phase. The presence of the μ phase could improve the compressive strength of Co28.5Cr21.5Fe20Ni26Mo4 MEAs. Meanwhile, the ductile FCC phase matrix could effectively suppress the propagation of cracks to improve its ductility. Hence, as-sintered MEAs possessed excellent compression properties, and the average compressive strength value was 2,606 MPa when the strain was 50%. Compared with as-sintered MEAs, the phase composition of as-annealed MEAs did not change. The micro-hardness of annealed MEAs was stable compared to as-sintered MEAs (342 HV), and its fluctuation was about ±30 HV. The compressive strength of the annealed MEAs did not alter greatly, and the maximum fluctuation value was only about 6.5%. Hence, Co28.5Cr21.5Fe20Ni26Mo4 MEAs had excellent thermal stability. Graphical Abstract

中文翻译：

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退火热处理对热等静压制备的非等原子CoCrFeNiMo中熵合金组织和力学性能的影响

摘要 在本研究中，采用热等静压法制备了非等原子 Co28.5Cr21.5Fe20Ni26Mo4 中熵合金 (MEA)。研究了退火热处理对MEAs显微组织和力学性能的影响。结果表明，烧结态合金的显微组织主要由面心立方（FCC）相和μ相组成。μ相的存在可以提高Co28.5Cr21.5Fe20Ni26Mo4 MEA的抗压强度。同时，延展性FCC相基体可以有效抑制裂纹扩展，提高其延展性。因此，烧结后的 MEA 具有优异的压缩性能，当应变为 50% 时，平均压缩强度值为 2,606 MPa。与烧结态 MEA 相比，退火态 MEA 的相组成没有变化。与烧结态 MEA（342 HV）相比，退火后的 MEA 的显微硬度稳定，其波动约为 ±30 HV。退火后的MEAs的抗压强度变化不大，最大波动值仅为6.5%左右。因此，Co28.5Cr21.5Fe20Ni26Mo4 MEAs 具有优异的热稳定性。图形概要