Unveiling deformation behavior of selective laser melted Al-doped CoCrNi medium entropy alloys

Abstract

This study investigates the effects of aluminum (Al) addition on the deformation behavior of CoCrNi medium entropy alloy (MEA) processed via selective laser melting (SLM). As-SLMed alloy exhibits a complex microstructure featuring various dislocation structures, nanoprecipitates, and stacking faults. Rolling deformation induces significant microstructural evolution, including the increased dislocation slip density, the formation of deformation bands and shear bands. The evolution of dislocation slip reveals three distinct deformation modes. The interplay between dislocations, stacking faults, and Lomer-Cottrell locks enhances the alloy's plastic deformation capacity. By calculating the twinnability of Al₈(CoCrNi)₉₂ by using first-principles calculation, the absence of deformation twinning is explained. Due to the dislocation-dominated deformation mechanism, the texture is primarily composed of Cu ({112}<111>) and Goss ({110}<001>) components.