Phase transformations in Titanium: Anisotropic deformation of ω phase

We study the plastic deformation of the ω phase which is obtained when Titanium undergoes a phase transformation under pressure. We perform molecular dynamics simulations under uniaxial loading and find that the ω phase not only shows brittle fracture upon loading in the [0001] direction, but also exhibits "superplastic" deformation features along the [100] 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 α (hcp) to ω (hexagonal) phase transformation. We further show that the elastic deformation of the m phase is anisotropic; it can be non-uniform upon [0001] uniaxial compression. Our results provide insight into the mechanical behaviour of the m phase and imply that the transformation mediated ductility can lead to improvement of the plasticity of co-containing Titanium alloys.