Micro-mechanisms of microstructural damage due to low cycle fatigue in CoCuFeMnNi high entropy alloy

Abstract

Low cycle fatigue behavior of equiatomic CoCuFeMnNi high entropy alloy was investigated under fully reversible strain control mode followed with detailed microstructural characterization using electron back scatter diffraction. There is an increase in the intragranular misorientation and geometrically necessary dislocation density with increase in the strain amplitude that leads to accumulation of damage and intergranular cracking. The interaction of dislocations with copper rich nano-clusters, solute environment and grain boundaries affect slip reversibility, thereby deciding cyclic deformation behaviour. Annealing twin boundaries are resistant to damage and increasing their population density by grain boundary engineering can improve performance of CoCuFeMnNi alloy.