  Faceted grain boundaries can migrate in interesting and unexpected ways. For
example, faceted {\Sigma}11 <110> tilt grain boundaries were observed to
exhibit mobility values that could be strongly dependent on the direction of
migration. In order to understand whether this directionally-anisotropic
mobility is a general phenomenon and to isolate mechanistic explanations for
this behavior, molecular dynamics simulations of bicrystals evolved under an
artificial driving force are used to study interface migration for a range of
boundary plane inclination angles and temperatures in multiple face centered
cubic metals (Al, Ni, and Cu). We find that directionally-anisotropic mobility
is active in a large fraction of these boundaries in Ni and Cu and should
therefore impact the coarsening of polycrystalline materials. On the other
hand, no such anisotropy is observed in any of the Al boundaries, showing that
this behavior is material-dependent. Migration of the faceted boundaries is
accomplished through transformation events at facet nodes and incommensurate
boundary plane facets, which are termed shuffling modes. Three major shuffling
modes have been identified, namely Shockley shuffling, slip plane shuffling,
and disordered shuffling. A shift from the first two ordered modes to the third
disordered mode is found to be responsible for reducing or removing
directionally-anisotropic mobility, especially at the highest temperatures
studied.
