On non-equilibrium grain boundaries and their effect on thermal and mechanical behaviour: a molecular dynamics computer simulation

Molecular dynamics simulation is used to study the tensile mechanical properties of face-centred cubic Ni nanocrystalline materials with mean grain size of 12 nm. Three samples are considered: one as-prepared, another annealed at 800 K, and one in which additional structural disorder has been introduced to the grain boundary region. From the room-temperature deformation properties, a reduction in plastic strain is observed when grain boundaries and triple junction regions approach more equilibrium conditions. It is also observed that similar atomic activity within the grain boundary region exists under both applied stress and high-temperature conditions, indicating a close relationship between atomic-scale relaxation and inter-grain deformation mechanisms within the nanocrystalline system.