采用单辊快速凝固法制备了厚度为50-70 μm的Cu₂₅Al₁₀Ni₂₅Fe₂₀Co₂₀高熵合金箔材, 并研究了其微观结构、抗拉强度、伸长率及电容储能焊特性. 结果表明, Cu₂₅Al₁₀Ni₂₅Fe₂₀Co₂₀高熵合金为fcc结构的单一相, 快速凝固使合金组织显著细化. 在电容储能焊条件下, 快速凝固高熵合金箔材点焊接头形成了形态规则的椭球状熔核, 熔核形核率较低, 晶体依附于母材局部半熔化的晶粒向熔核心部生长, 最终形成发达的树枝晶组织; 熔合线清晰; 与熔核毗邻的母材组织未观察到粗化迹象. 电容储能焊条件下, 贯穿性裂纹是高熵合金焊接接头中的主要焊接缺陷, 其与高熵效应导致的熔核区晶粒粗化、晶体生长方向及电极压力密切相关.

High-entropy alloys are prospective functional and structural materials owing to their excellent electromagnetic and mechanical properties. In this paper, the quenched Cu25Al10Fe20Co20Ni25 alloy foils with the thickness of 50~70 μm are obtained via a single roller experimental apparatus. Furthermore, the microstructure and properties of alloy foils are studied and the rapid solidification joining is conducted by using a micro-type capacitor discharge welding machine. The results show that Cu25Al10Fe20Co20Ni25 high-entropy alloy presents a simple single-phase FCC structure and its as-cast microstructure is coarsening. Rapid solidification can make the grains fine remarkably. The microstructure of joint is characterized by rapid solidification, while the microstructure in nugget is coarse and has clear directivity compared with the ordinary nuggets. The base microstructure adjacent to nugget has no evidence of coarsening and the width of fusing zone is almost tending to 0. Penetrated crack is the main defect during welding of high-entropy alloy, which relates to the microstructural coarsening and directionality resulting from high-entropy effects as well as electrode press.