Molecular dynamics simulation of diffusion and its microscopic mechanism in CoNi-containing multi-principal element alloys

Multi-principal element alloys have become one of the new hotspots in the development of materials because of their excellent properties, which are thought to be highly related to the diffusion ability. Comparing the past studies focusing on few alloys, the paper investigates the diffusion behavior of all containing CoNi sub-systems from binary CoNi alloy to quinary FeCrMnCoNi alloy using molecular dynamics simulations. By comparing migration energy, mean squared displacement, correlation factors in each alloy, it was fund that the average migration energy and correlation factors are the key factors affecting the diffusion ability in multi-principal element alloys. Meanwhile, a type of trap positions is suggested whose amount also affects the diffusion ability of the alloy to some extent. The conclusion not only promotes the theoretical development for diffusion in multi-principal element alloys but also is helpful for alloy design.