Ab initio reappraisal of the dislocation-associated stacking faults in hcp titanium: a new dissociation mechanism

Abstract

The slip is a secondary slip system in hexagonal close-packed metals which is often activated when they undergo a c-axis deformation. The behaviour of the screw dislocation remains unclear. Via ab initio calculations with an all atom all direction relaxation method, we find a stable 0.57 stacking fault on plane () and a stable nanotwinned 0.215 stacking fault on plane () in -Ti. Based on these results, we propose a screw dislocation dissociation mechanism which allows a split to three partials. This suggests a more complex screw dislocation-related cross-slip mechanism.

Keywords:

• First-principles
• stacking faults
• dislocation dissociation

Acknowledgements

The authors acknowledge a partial support by the French Agence Nationale de la Recherche under Grant ANR-10-BLAN-915 FLUTI. L. Liang, benefited from a CEA PhD grant.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was performed using HPC resources from GENCI-CINES/IDRIS [grant 2014-i2014097223], [grant number 2015-x2015097223]; École Polytechnique through the LLR-LSI project; French Agence Nationale de la Recherche [grant number ANR-10-BLAN-915 FLUTI]. L. Liang, benefited from a CEA PhD grant.