Decoupling the chemical-ordering-dependent dislocation and diffusion contributions to creep in multi-principal element alloy

Abstract

In multi-principal element alloys, dislocation motion and lattice diffusion are two key plasticity carriers, which are strongly interacted with the local chemical order. While in creep deformation, the difference between the impediment of the local chemical order on dislocation motion and lattice diffusion, along with the temperature dependency of such difference, is an intriguing topic that remains unsolved. By atomistic simulations on a typical NiCoCr system and rationalization with classic constitutive models, we found that the lattice diffusion receives less impediment compared to dislocation glide so that transition of creep mechanisms presents in a chemically ordered system. The critical stress of transition is tuned by temperature.