Gradient-structured ferrous medium-entropy alloys with enhanced strength-ductility synergy by ultrasonic nanocrystalline surface modification

Abstract In this study, gradient-structured Fex(CoNi)90−xCr10 ferrous medium-entropy alloys were fabricated by using an ultrasonic nanocrystalline surface modification process. The processed alloys with gradient structures exhibited the improved room-temperature yield strength by up to 158% and tensile strength by up to 31% at reasonable ductility compared to homogeneous microstructured counterparts.