Atomistic Simulation of a Neighbor-Switching Event in the Deformation of a Model Polycrystal

摘要

This paper describes the simulated atomistic process in a large deformation of polycrystalline matter. Molecular dynamics method was applied to a model polycrystal of yttria-stabilized zirconia composed of eight small grains to investigate the microscopic mechanism of superplastic deformation. During the tensile deformation up to the strain of 0.55, a neighbor-switching event of grains similar to that proposed by Ashby and Verrall was observed in the present simulation. The large strain was accomplished by non-uniform diffusional flows in the polycrystal. By analyzing the diffusive motions of oxide ions, the mass transport during the deformation was found to take place mainly in the boundary layer of about 1 nm thickness, which covers about 0.4 times of the total volume. This result is different from the quasi-uniform flow expected in the classical creep models, but is consistent with the Ashby and Verall's model.