Phase transformations in Titanium: Anisotropic deformation of omega phase

HX Zong and DZ Xue and XD Ding and T Lookman, 18TH APS-SCCM AND 24TH AIRAPT, PTS 1-19, 500, 112042 (2014).

DOI: 10.1088/1742-6596/500/11/112042

We study the plastic deformation of the omega phase which is obtained when Titanium undergoes a phase transformation under pressure. We perform molecular dynamics simulations under uniaxial loading and find that the omega phase not only shows brittle fracture upon loading in the 0001 direction, but also exhibits "superplastic" deformation features along the 10 (1) over bar0 direction. The brittle fracture is analogous to that which occurs in metallic glass by means of shear banding whereas the ductility is mediated by the a (hcp) to alpha (hexagonal) phase transformation. We further show that the elastic deformation of the omega phase is anisotropic; it can be non-uniform upon 0001 uniaxial compression. Our results provide insight into the mechanical behaviour of the omega phase and imply that the transformation mediated ductility can lead to improvement of the plasticity of omega-containing Titanium alloys.

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