Zigzag configuration of mechanical twin and stress-induced omega phase in metastable β Ti–34Nb (at.%) alloy

Abstract

A zigzag configuration of {112}〈111〉 mechanical twin and stress-induced omega phase with habit plane of {0−110}ω//{2−1−1}β was observed by TEM in a metastable β Ti–34Nb (at.%) alloy after compression at room temperature. The zigzag configuration can be formed by the movement of three-layer homogeneous 1/6〈111〉 and inhomogeneous 1/12〈111〉, 1/3〈111〉, and 1/12〈111〉 shears on consecutive {112} planes, respectively resulting from dissociation of a perfect 1/2〈111〉 screw dislocation and the cross-slip of the screw dislocation when it is blocked at the obstacle. The stacking fault energy of the β phase is a key factor for the formation of such zigzag configuration in the deformed β Ti–34Nb (at.%) alloy.