A new method for preparing high entropy alloys: Electromagnetic pulse treatment and its effects on mechanical and corrosion properties

Electromagnetic pulse (EMP) treatment was firstly applied during the preparation process of CoCrFeNiCu high entropy alloy (HEA) and its mechanism was illustrated. The crystal structure, microstructure, mechanical properties, and corrosion properties of CoCrFeNiCu HEAs in current and magnetizing directions with different EMP frequencies were characterized. The results demonstrated that EMP can significantly influence the lattice parameter, microstructure, enhance mechanical and alter corrosion properties. When EMP applied, the dendrite arms were severely coarsened and the microstructure changed from typical dendrite to quasi-equiaxed morphology. The hardness and yield strength were increased by 18% and 23%, respectively. Meanwhile, corrosion current density decreased from 5.4 μA cm−2 to 1.4 μA cm−2. Anisotropy effect was revealed between the current and magnetizing directions in the same ingot, which is seldom reported before. The gap of interplanar distances, mechanical properties and corrosion properties between these two perpendicular directions became smaller and close to each other with increasing EMP frequency.