CoCrNiCu_x (x = 0.16, 0.33, 0.75, and 1) without macro-segregation medium-entropy alloys (MEAs) was prepared using laser directed energy deposition (LDED). The microstructure and mechanical properties of CoCrNiCu_x alloys with increasing Cu content were investigated. The results indicate that a single matrix phase changes into a dual-phase structure and the tensile fracture behaviors convert from brittle to plastic pattern with increasing Cu content in CoCrNiCu_x alloys. In addition, the tensile strength of CoCrNiCu_x alloys increased from 148 to 820 MPa, and the ductility increased from 1 to 11% with increasing Cu content. The nano-precipitated particles had a mean size of approximately 20 nm in the Cu-rich phase area, and a large number of neatly arranged misfit dislocations were observed at the interface between the two phases due to Cu-rich phase precipitation in the CoCrNiCu alloy. These misfit dislocations hinder the movement of dislocations during tensile deformation, as observed through transmission electron microscopy. This allows the CoCrNiCu alloy to reach the largest tensile strength and plasticity, and a new strengthening mechanism was achieved for the CoCrNiCu alloy. Moreover, twins were observed in the matrix phase after tensile fracture. Simultaneously, the dual-phase structure with different elastic moduli coordinated with each other during the deformation process, significantly improving the plasticity and strength of the CoCrNiCu alloy.

 使用激光定向能量沉积 (LDED) 制备没有宏观偏析中熵合金 (MEA) 的CoCrNiCu _x ( x = 0.16、0.33、0.75和 1)。研究了随着Cu含量增加的CoCrNiCu _x合金的显微组织和力学性能。结果表明，随着CoCrNiCu _x合金中Cu含量的增加，单一基体相转变为双相结构，拉伸断裂行为从脆性转变为塑性模式。此外，CoCrNiCu _x的抗拉强度合金从 148 MPa 增加到 820 MPa，随着 Cu 含量的增加，延展性从 1% 增加到 11%。在富铜相区，纳米析出颗粒的平均尺寸约为 20 nm，由于富铜相在 CoCrNiCu 合金中析出，在两相界面处观察到大量排列整齐的错配位错. 通过透射电子显微镜观察到，这些错配位错阻碍了拉伸变形过程中位错的运动。这使得 CoCrNiCu 合金达到最大的抗拉强度和塑性，并为 CoCrNiCu 合金实现了一种新的强化机制。此外，在拉伸断裂后的基体相中观察到孪晶。同时，