研究了CoCrFeNiCu高熵合金(HEA)和304不锈钢(304SS)在不同温度下的固相扩散焊，通过SEM、EBSD、TEM及XRD分析了扩散焊后的组织变化、晶体类型的转变以及相析出，并进行了力学性能测试。结果显示：固相扩散能实现2种合金的连接，低温下界面处残留有孔洞；随着温度的升高，扩散能力增强，界面处气孔消失，变得致密；在扩散层内没有发现金属间化合物，形成了全固溶组织，扩散层的厚度在10~31 μm之间；硬度测试显示，CoCrFeNiCu HEA-扩散层-304SS母材硬度呈梯度增加，晶体结构类型以亚结构和再结晶结构为主，小角度晶界占93%；拉伸强度测试显示，材料均断裂于HEA母材处，焊接接头的强度高于母材，实现了高质量连接。

During fusion welding of the Cu-containing high-entropy alloy (HEA) of CoCrFeNiCu, Cu precipitates at the grain boundary and reduces the welding quality and mechanical properties. Solid-phase diffusion welding is connected with the diffusion of elements, which reduces the segregation of Cu and solves this problem well. In the present work, the study of diffusion welding of CoCrFeNiCu HEA with 304 stainless steel (304SS) was carried by SEM, EBSD, TEM, and XRD. The properties of the microstructure and crystal type were obtained. The results show that element diffusion can achieve high-quality connection between the two metals. As the temperature increases, the diffusion capacity increases. The pores at the interface disappear. The thickness of the diffusion layer is between 10-31 μm, without forming intermetallic compound, which shows that a solid solution microstructure is formed after diffusion. According to the XRD, this microstructure is mainly as CoCrFeNiCuMn, that leads to an improvement in the mechanical properties. The hardness of the CoCrFeNiCu HEA-diffusion layer-304SS shows a gradient increase. The crystal structure type is mainly as substructured and recrystallized structure. The proportion of low-angle grain boundaries is 93% in the diffusion layer. The EBSD test results show that the grain orientation of the welded joint (diffusion layer) has changed, mostly concentrated on the (111) plane. This also causes anisotropy of the mechanical properties. Tensile performance test showed that the material fractured in the CoCrFeNiCu HEA base material area. These show that diffusion welding achieves a high-quality connection of the two materials.