Molecular dynamics study on the dislocation evolution mechanism of temperature effect in nano indentation of FeCoCrCuNi high-entropy alloy

In this paper, the atomic model of high-entropy alloy is established by molecular dynamics simulation. By applying nano-indentation, the influence of Cu atomic ratio and temperature on the deformation of FeCoCrCuNi high-entropy alloy was studied, and the micro-scale dislocation movement evolution mechanism was obtained. The results show that, with the increase of temperature, the load of FeCoCrCuNi high-entropy alloy under nano indentation decreases. The total length of dislocations in each stage of nanoindentation decreases monotonically, and the types of dislocation reactions decrease. Under the action of high temperature, the number of perfect dislocations decomposed into Shockley partial dislocations decreases, resulting in more Frank dislocations and Stair-rod dislocations, which makes the extended dislocations recombine into perfect dislocations, and the length of dislocations decreases sharply. The dislocation defect is replaced by a cavity at high temperature, which makes the high-entropy alloy lose elastoplastic mechanical properties.