We report molecular-dynamics simulations of plastic deformation of Ni nanophase samples with different grain structures, temperature, and applied stress. We analyze the mechanical and thermal activation of the elementary process contributing to plastic deformation at the grain boundaries and provide a quantitative interpretation in terms of a general nonlinear viscous behavior whose temperature, stress, and grain-size dependence is determined.

• Received 1 April 1998

DOI:https://doi.org/10.1103/PhysRevB.58.11246