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Effect of solute segregation on shear-induced grain boundary motion

Atomic-scale simulations are performed to study the effect of solute segregation on the shear-induced motion of select grain boundaries in the classical $α$-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.