Curvature-driven migration of a series of <110> tilt grain boundaries in a body-centered cubic Fe-20Cr alloy was simulated using molecular dynamics to investigate the relationship between the atomic migration mechanism and mobility at medium to high temperatures. The boundaries studied included low-angle boundaries, high-angle boundaries and singular boundaries such as coherent twins. The steady-state boundary shape and curvature were compared with a simple analytical model which incorporated the dependence of absolute mobility and free energy upon boundary inclination. The comparison indicated that the 109.5° (11¯2) Σ3 coherent twin boundary would have a relatively low energy but high mobility. This result was attributed to a particularly effective repeated shuffle mechanism which occurred on the twinning plane. Two other migration mechanisms were observed: one involving the motion of <111> glissile dislocations in low-angle boundaries and the other involving uncorrelated atomic shuffles in high-angle boundaries sometimes associated with interfacial steps.

A Molecular Dynamics Study of Grain Boundary Free Energies, Migration Mechanisms and Mobilities in a BCC Fe-20Cr Alloy. Toda-Caraballo, I., Bristowe, P.D., Capdevila, C.: Acta Materialia, 2012, 60[3], 1116-28