Atomic-scale analysis of nanoindentation behavior of high-entropy alloy

Abstract

Using molecular dynamics simulations, we study the elastic and plastic deformations of indentation in FeCrCuAlNi high-entropy alloy (HEA). The indentation tests are carried out using spherical rigid indenter to investigate the effects of high-entropy and severe lattice distortion in terms of shear strain, indentation force, surface morphology, defect structure, dislocation evolution and radial distribution function on the deformation processes. It can be found that when the indentation depth increases, the shear stress requires for the occurrence of the contact area between the indenter and the substrate increased, which is attributable to a higher probability to observe the dislocation evolution under a large indentation depth. The indentation test also shows that the equal element addition can significantly improve the mechanical properties of HEA compared with the conventional alloy. Based on the Hertzian fitting, the FeCrCuAlNi HEA has the Young’s modulus of 161[Formula: see text]GPa and hardness of 15.4[Formula: see text]GPa, respectively. These values are higher than that of traditional metal materials, due to the low stacking fault energy and the dense atomic arrangement in the slip plane of HEA. In the plastic region, the Fe element causes the more stable crystal structure, much stronger than the Cu element, presumably resulted from a variety of crystal structures for Fe in the multicomponent FeCrCuAlNi alloy. Further, this effective strategy is used to accelerate the discovery of excellent mechanical properties of HEAs.