Forced Chemical Mixing in Alloys Driven by Plastic Deformation

Abstract

Molecular dynamics simulations of forced atomic mixing in crystalline binary alloys during plastic deformation at 100 K are performed. Nearly complete atomic mixing is observed in systems that have a large positive heat mixing and in systems with a large lattice mismatch. Only systems that contained a hard precipitate in a soft matrix do not mix. The amount of mixing is quantified by defining a mean square relative displacement of pairs of atoms, ${\sigma }^2(R,t)$, that were initially separated by a distance $R$. Analysis of ${\sigma }^2(R,t)$ and visual inspection of the displacement fields reveal that forced mixing results from dislocation glide, and that it resembles the forced mixing of a substance advected by a turbulent flow. Consideration of ${\sigma }^2(R,t)$ also provides a rationalization of compositional self-organization during plastic deformation at higher temperatures.