Evolution of microstructure and texture in Al-containing CoCrNi medium entropy alloys during severe warm-rolling

Abstract

Al, as an alloying element, can influence the properties of the single-phase equiatomic CoCrNi MEA. In this study, different alloys of different Al concentrations added to CoCrNi MEA (AlxCoCrNi) were prepared by warm rolling to understand the effect of Al. The alloys were warm-rolled at 400 °C up to an 85% thickness reduction, followed by isochronal annealing at 700–1100 °C. The microstructure after deformation reveals the development of deformation heterogeneities such as shear bands and deformation nano-twins. The evolution of the weak brass component is seen after deformation. Different phases, such as BCC and sigma, evolve upon annealing treatment at different temperatures. The higher Al-content MEA (Al9.09) shows comparatively finer recrystallized microstructure irrespective of the annealing temperatures. Also, weak recrystallization texture develops after annealing, and the deformation texture components lying on α-fiber are preserved. This indicates the absence of preferential nucleation and growth during annealing. The hardness in the as-cast, deformed, and annealed conditions increases with increasing Al content, indicating the influence of Al in the strengthening of the AlxCoCrNi MEAs.