Atomic-scale analysis of mechanical and wear characteristics of AlCoCrFeNi high entropy alloy coating on Ni substrate

Abstract

High entropy alloys (HEAs) are potential materials for coating due to their high hardness and wear resistance. This study builds molecular dynamics models to explore the mechanical characteristic and wear behavior of AlCoCrFeNi HEA coating on Ni substrate during scratching. The scratching force and friction coefficient of HEA coating on Ni are larger than the pure Ni due to the HEA coating with high strength and good adhesion. The Ni substrate protection mechanism exhibits deformation absorbed by the HEA coating, so the shear strain of HEA coating is more severe than the pure Ni. The Ni substrate is protected by HEA coating, which causes less wear, as shown by the higher wear atom number of pure Ni than the HEA coating on Ni. More resistance to tool motion as increased scratching depth results in an increased friction coefficient, while the friction coefficient decreases with increasing scratching speed due to the influence of thermal softening and strain rate hardening. The accumulation of scratched atoms and energy due to insufficient relaxation time around the tool leads to considerable deformation and temperature increase. The HEA coating reduces the wear of Ni substrate when the scratching depth is smaller than the HEA coating thickness.