Dependence of mechanical and surface properties on crystallographic orientation, twin boundaries, and temperature in CoCrFeMn0.3Ni high-entropy alloys

Abstract

The CoCrFeMnNi high-entropy alloy (HEA) has been widely studied for its mechanical properties and thermal stability, yet its tribological behaviour remains under explored. In this article, we investigate the effects of temperature and twin boundary spacing on the surface nanotribological properties and subsurface damage of CoCrFeMn0.3Ni HEA through molecular dynamics simulations. Among the orientations, [001] exhibits the highest friction coefficient, indicating the greatest restriction to indenter movement. Higher temperatures reduce wear rates, showing good thermal stability, likely due to thermal softening that decreases high-stress regions and the driving force for dislocation nucleation. Monocrystalline HEA shows lower scratch resistance than twinned workpieces. The loading force correlates with twin boundary distance, with twins increasing strength but excessive twins causing softening. Material removal becomes easier in large twinned workpieces. In monocrystalline HEA, plastic deformation is dominated by partial dislocation slip. However, in twinned workpieces, there are not only partial dislocation slips but also dislocation slips parallel to the twin and twin migration. These findings have important implications for HEA design and their applications in extreme conditions.