On the Origin of Recovery-Induced Strengthening in CoCrNi Alloy

Strengthening during low-temperature annealing is a common observation in several nanocrystalline and ultrafine-grained materials. The origin of such strengthening is generally attributed to various recovery processes leading to restricted dislocation motion. Herein, the observations on recovery-induced strengthening in cold-rolled (CR) equiatomic CoCrNi alloys are presented. An increase in hardness is observed for samples deformed to thickness reduction of 35–80% after 2 h of annealing at 500 °C. A detailed microstructural investigation of 80% CR and subsequently annealed samples suggests that both dislocation density and local chemical composition play important role in strengthening. Further, uniaxial tensile tests elucidate the importance of mobile dislocations on strength and ductility of annealed samples.