Ti合金の変形モード変化に対する合金元素の影響：第一原理計算

抄録

The deformation mode of some titanium alloys differs from that of pure Ti because of the presence of a secondary phase and alloying elements in the α-phase. We investigated the effect of Al and V solutes as typical additive elements on the dislocation motion in Ti alloys using density functional theory calculations. To clarify the energy differences between various dislocation cores, we evaluated possible core structures and motion in various slip planes. The energy difference between most stable pyramidal and prismatic cores is very small, whereas that between the prismatic and basal cores is larger, thereby preventing dislocation motion in the basal plane in pure Ti. However, the Peierls barrier for motion in the basal plane is not as high if the dislocation exists in the basal core. Direct calculations for the dislocation core around solutes revealed that Al solute facilitate dislocation motion in the basal plane by reducing the energy difference between the core structures while these solutes have a reverse trend for the interaction energy with the dislocation core.