Modeling of pseudotwinning in Fe_3Ga

摘要

Pseudotwinning is an important deformation mechanism that can produce reversible deformations similar to the shape memory phenomenon. Pseudotwinning merits further consideration from a modeling viewpoint as it could open new frontiers for discovery of alloys with recoverability of deformation. In this study, we focus on the Fe_3Ga (D0_3 and L1_2 lattices) with atomistic simulations. We present a pseudotwin nucleation model based on the generalized planar fault energy from first-principles calculations. The minimization of the total energy at the mesoscale associated with pseudotwin nucleation leads to determination of the twinning stress. The low energy barriers and twinning stress demonstrate that pseudotwinning in D0_3 Fe_3Ga is a possible deformation mode, but pseudotwinning is unlikely to occur in L1_2 Fe_3Ga due to the significantly high energy barrier and twinning stress. The predicted twinning stress is compared with experimental measurements, and the results show very good agreement. Hence, we suggest that the results provide a quantitative methodology to understanding and determining pseudotwinning in ordered alloys.