Dislocation self-interaction in TiAl: Evolution of super-dislocation dipoles revealed by atomistic simulations. (10th April 2021)

• Record Type: Journal Article
• Authors: Zhen, Z.; Wang, H.; Teng, C.Y.; Bai, C.G.; Xu, D.S.; Yang, R.
• Is Part Of: Journal of materials science & technology. Volume 69(2021)
• Page Start: 138
• Page End: 147
• Publication Date: 2021-04-10
• Subjects: TiAl -- Dislocation -- Dipole -- Mechanical property -- Atomistic simulation; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2020.03.091
• Languages: English
• ISSNs: 1005-0302

Abstract

Abstract: 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, super-dislocation dipoles in γ-TiAl and α2 -Ti3 Al 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 -Ti3 Al exhibit similar features as fcc and hcp metals, respectively. Generally, over long-term annealing where diffusion is significant, 60° super-dipoles in γ-TiAl are stable, whereas the stability of super-dipoles in α2 -Ti3 Al 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.