[PO-N2] Poster Session 2

[P2-76] Vacancy segregation analysis near grain boundaries in metallic systems by long-time atomistic simulations

^○Shotaro Hara (Dept. of Mechanical Engineering, Chiba Institute of Technology, Japan)

Long-term degradation phenomena in metallic systems under a high temperature, such as creep voiding, are governed by the vacancy diffusion, accumulation and growth processes at an atomistic scale around the material heterogeneities like grain boundaries. However, the basic properties such as the equilibrium vacancy concentrations and the kinetics near grain boundaries are not still understood because a molecular dynamics simulation often suffers from tracking thermally-activated processes due to its limited time scale. In this study, the vacancy segregation behavior at grain boundary has been analyzed using diffusive molecular dynamics simulations, which is a novel approach for exploring the atomic level mass action along the chemical potential gradient at diffusive time scale. The equilibrium vacancy concentrations and the chemical potential distributions at grain boundaries are computed for the different grain boundary character. The correlation between the grain boundary energies and their concentrations have also been considered. Furthermore, the kinetic nature of grain boundary sliding was investigated using this new scheme and the effect of stress on the sliding was discussed.