A molecular dynamics simulation study of the migration of individual grain boundary triple junctions was presented. The simulation cell was designed so as to attain steady-state migration, and observations of the triple-junction angle and grain-boundary profile confirmed that such a steady state was reached. The static equilibrium grain-boundary triple-junction angles and dynamic triple-junction angles were measured as a function of the grain size and grain-boundary misorientation. In most cases, the static and dynamic triple-junction angles were almost identical, but appreciable differences were observed for low-Σ boundary misorientations. Intrinsic steady-state triple-junction mobilities were deduced from measurements of the rate of change of grain-boundary area in simulations, with and without triple junctions. The triple-junction velocity was found to be inversely proportional to the grain size. The normalized triple-junction mobility exhibited marked variations with boundary misorientation; with strong minima at misorientations that corresponded to low values of Σ. The triple junctions created a substantial drag on grain-boundary migration for low-mobility misorientations.

Triple Junction Mobility - a Molecular Dynamics Study. M.Upmanyu, D.J.Srolovitz, L.S.Shvindlerman, G.Gottstein: Interface Science, 1999, 7[3-4], 307-19