Effect of solute segregation on shear-induced grain boundary motion

TL;DR

This study uses atomic-scale simulations to explore how solute segregation influences shear-induced grain boundary motion in alpha-Fe/C, revealing transitions between coupled motion and sliding depending on shear rate and solute excess.

Contribution

It provides new insights into how solutes affect grain boundary dynamics under shear, highlighting the roles of diffusion and bicrystallography in this process.

Findings

Transition from coupled motion to sliding at high shear rates

Boundaries detach from solute clouds below critical solute excess

Extrinsic coupled motion occurs at low stresses and shear rates

Abstract

Atomic-scale simulations are performed to study the effect of solute segregation on the shear-induced motion of select grain boundaries in the classical $\alpha$-Fe/C system. At shear rates larger than the solute diffusion rate, we observe a transition from coupled motion to sliding. Below a critical solute excess, the boundaries break away from the solute cloud and move in a coupled motion. At smaller shear rates, we observe extrinsic coupled motion at small stresses indicating that the coupling is aided by convective solute diffusion along the boundary. Our studies underscore the role of solutes in modifying the bicrystallography, temperature and rate dependence of shear accommodation at grain boundaries.