Monte Carlo simulations, combined with embedded-atom method potentials, were used to investigate Σ = 5 tilt grain boundary sliding. Atomic structures, and grain boundary sliding/migration energy profiles, were studied at high temperatures in the absence or presence of vacancies. The annealing temperature was found to play an important role in determining the grain boundary energetics and mobility. Simulated annealing produces new lower-energy states of the complex low-symmetry grain boundary structure. The vacancy formation energy in the first layer from the interface was found to be appreciably lower than that in other layers or in the bulk. A vacancy at the interface had a significantly higher formation energy when compared with the bulk; in excellent agreement with ab initio electronic-structure calculations. For both static and simulated annealing simulations, the grain boundary sliding energy profile was smooth. It exhibited several energy peaks and valleys; with the latter being associated with grain boundary migration. The simulated annealing method reduced the grain boundary sliding/migration energy barrier by a factor of about 3, and increased the rate of migration. The distribution of atomic energies helped in identifying the atoms which played a key role in grain boundary sliding and migration. The grain boundary sliding energy profile, in the presence of a vacancy placed in the first layer, was very similar to that of the clean boundary. A vacancy at the interface increased the grain boundary energy and led to no migration.

Grain Boundary Sliding and Migration - Effect of Temperature and Vacancies. P.Ballo, N.Kioussis, G.Lu: Physical Review B, 2001, 64[2], 024104 (7pp)