Dislocation self-interaction in TiAl: Evolution of super-dislocation dipoles revealed by atomistic simulations

• 作者: Z.Zhen H.Wang C.Y.Teng C.G.Bai D.S.Xu R.Yang
• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2021,（10）
• 页码范围: 138-147
• 页数: 10页
• 语种: 英文

摘要

As one of the fundamental outcomes of dislocation self-interaction,dislocation dipoles have an important influence on the plastic deformation of materials,especially on fatigue and creep.In this work,superdislocation dipoles in γ-TiAl and α2-Ti3Al were systematically investigated by atomistic simulations,with a variety of dipole heights,orientations and annealing temperatures.The results indicate that non-screw super-dipoles transform into locally stable dipolar or reconstructed cores at low temperature,while into isolated or interconnected point defect clusters and stacking fault tetrahedra at high temperature via short-range diffusion.Non-screw super-dipoles in γ-TiAl and α2-Ti3Al exhibit similar features as fcc and hcp metals,respectively.Generally,over long-term annealing where diffusion is significant,60° superdipoles in γ-TiAl are stable,whereas the stability of super-dipoles in α2-Ti3Al increases with dipole height and orientation angle.The influence on mechanical properties can be well evaluated by integrating these results into mesoscale or constitutive models.