MICROSTRUCTURE AND CAPACITOR DISCHARGE WELDING CHARACTERISTICS OF QUENCHED Cu25Al10Ni25Fe20Co20 HIGH-ENTROPY ALLOY FOILS

High-entropy alloys are prospective functional and structural materials owing to their excellent electromagnetic and mechanical properties. In this paper, the quenched Cu25Al10Fe20Co20Ni25 high-entropy alloy foils with the thickness of 50-70 mu m were obtained via a single roller experimental apparatus, and the microstructure, tensile strength, elongation and capacitor discharge welding (CDW) characteristics of the alloy were studied. The results show that the high-entropy alloy has a simple single-phase fcc structure, and the microstructure is refined remarkably by rapid solidification. Under CDW condition, the joint with a regular spheroidicity nugget forms. Due to lower nucleation rate and epitaxial growth based on semi-molten grains of base metal to the center of nugget, the microstructure of nugget consists of coarse dendrite crystals. The fusion line is clear between nugget and base metal, and the microstructure adjacent to nugget has no evidence of coarsening. Penetrated crack is the main defect during welding of high-entropy alloy, which relates to grain coarsening and crystal orientation resulting from high-entropy effects as well as electrode press.