The structure and motion of incoherent Σ3 grain boundaries in FCC metals

Abstract: Synthetic driving force molecular dynamics simulations were utilized to survey grain boundary mobility in three classes of incoherent {\Sigma}3 twin boundaries: <112>, <110>, and <111> tilt boundaries. These boundaries are faceted on low energy planes, and step flow boundary motion occurs by glide of the triplets of partial dislocations that comprise the mobile facets. Systematic trends with inclination angle are identified and characterized. Observations of thermally activated, anti-thermal, and athermal motion are explained in terms of the orientation of the Shockley partial dislocations along close-packed and non-close-packed directions. Thermally activated boundaries follow a compensation effect associated with a facet roughening transition. As for all faceting boundaries, system size and driving force must be chosen with care to prevent simulation artifacts.