Grain boundary finite length faceting Original Research Article

We study symmetrical and asymmetrical aluminium grain boundary faceting with molecular dynamics simulations employing two embedded atom method potentials. Facet formation, coarsening, and the reversible phase transition of image boundary into image twin, and vice versa, are demonstrated in the simulations and the results are consistent with earlier experimental studies and theoretical models. The image boundary shows faceting into image and image boundaries and coarsens with a slower rate when compared to image facets. However, facets formed by image and image boundaries from a image boundary are stable against finite temperature annealing. In the above faceted boundary, elastic strain energy induced by atomic mismatch across the boundary creates barriers to facet coarsening. Grain boundary tension is too small to stabilize the finite length faceting in both image twin and asymmetrical image and image facets. The observed finite facet sizes are dictated by facet coarsening kinetics which can be strongly retarded by deep local energy minima associated with atomic matching across the boundary.