粒界破壊現象の支配因子: 原子シミュレーションによる考察

抄録

The dominant factors influencing grain-boundary fracture phenomena are investigated through molecular dynamics simulations. We modeled symmetric tilt grain boundaries in Nickel, which have 12 different grain boundary misorientations, and subjected them to tensile deformation. Here, we focus on the surface energy, grain boundary energy, plastic work, and effective surface energy. The energy release modes were classified into four distinct categories. Notably, in models that did not exhibit significant plastic deformation, a clear correlation emerged between the difference in surface energy and grain boundary energy and fracture stress. On the other hands, in the case of GBs where dislocations are emitted, the fracture stress does not show clear correlation with the effective surface energy taking the plastic work into account. This suggests that plastic deformation based on the grain boundary structure contributes to the formation of the stress concentration at the grain boundary, resulting in the promotion of grain-boundary fracture.