Surface modification techniques, such as shot peening and ultrasonic nanocrystal surface modification, are widely used to improve wear, corrosion, and fatigue resistance, as well as strength by tailoring the near-surface microstructure. However, the severe plastic deformation accompanying these processes often results in high dislocation densities and limited strain accommodation capability, leading to a deterioration of ductility. In this study, argon plasma bombardment introduces a graded compressive residual stress field at the surface while reducing dislocation density in a CoCrFeMnNi high-entropy alloy. This surface modification simultaneously increases yield strength, tensile strength, uniform elongation, and total elongation, demonstrating a simple route to enhance strength–ductility synergy without severe surface deformation.
Kim et al. (Sat,) studied this question.