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

• 作 者: Z.Zhen H.Wang C.Y.Teng C.G.Bai D.S.Xu R.Yang
• 机 构: Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;School of Materials
• 出 处: 材料科学技术（英文版）
• 发表日期: 2021年10期
• 关键词: TiAl Dislocation Dipole Mechanical property Atomistic simulation

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.