Transformation-induced plasticity in omega titanium

Abstract

ω-titanium (Ti) is a high-pressure phase that is conventionally perceived to be brittle and nondeformable, although direct investigations of its deformation process remain scarce. In this work, we perform molecular dynamics simulations to study the deformation process of ω-Ti with initial defects and find that stress-induced ω → α martensitic transformation can cause extensive plasticity in ω-Ti under various loading directions. Moreover, for the first time, we demonstrate that four types of transformation twins-{ 11 2 ¯ 1 }, { 11 2 ¯ 2 }, { 10 1 ¯ 2 }, and { 10 1 ¯ 1 } twins-can be formed through the ω → α martensitic phase transformation. This work advances the understanding of plastic deformation in ω-Ti and unveils the essential role of the metastable ω-phase in the formation of transformation twins.