In order to reveal the effect of Mo addition on the microstructure and mechanical properties, (CoCuFeNi)_100-xMo_x (x = 0, 10, 15, 19, and 25, x values in atomic ratio) high entropy alloys were prepared by vacuum arc-melting. The results showed that with Mo addition, the μ phase formed and serious separation occurred in the high entropy alloys. The content of μ phase increased with the increase in Mo content. The microstructure of the alloys changed from an initial single-phase face-center-cubic (FCC) solid solution structure (x = 0) to a hypoeutectic microstructure (x = 15), then to a full eutectic microstructure (x = 19), and finally to a hypereutectic microstructure (x = 25). Coherent interface between μ phase and FCC phase was observed. The (CoCuFeNi)₈₁Mo₁₉ alloy with fully eutectic microstructures exhibited the highest yield strength of 557 MPa and fracture strength of 767 MPa in tensile tests at room temperature. The fracture surface revealed that the formation of great amounts of the μ phase resulted in the loss of ductility of (CoCuFeNi)_100-xMo_x alloys.

中文翻译：

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钼对CoCuFeNi高熵合金组织和力学性能的影响

为了揭示钼添加对显微组织和力学性能的影响，制备了（CoCuFeNi）_{100- x} Mo _x（x = 0、10、15、19和25，x原子比为x值）高熵合金。真空电弧熔炼。结果表明，添加Mo会在高熵合金中形成μ相，并发生严重的分离。μ相的含量随着Mo含量的增加而增加。合金的微观结构从最初的单相面心立方（FCC）固溶体结构（x = 0）变为亚共晶组织（x = 15），然后变为全共晶组织（x= 19），最后是过共晶微观结构（x = 25）。观察到μ相和FCC相之间的相干界面。具有完全低共熔组织的（CoCuFeNi）₈₁ Mo ₁₉合金在室温下的拉伸试验中显示最高的屈服强度为557 MPa，断裂强度为767 MPa。断裂表面表明，大量μ相的形成导致（CoCuFeNi）_{100- x} Mo _x合金的延展性损失。