Characterization of deformation localization in cold-rolled metastable β-Ti–Nb–Ta–Zr alloy

The deformation-induced microstructural variation in the metastable β-type biomedical Ti–35Nb–5Ta–7Zr (wt.%) alloy subjected to multi-pass cold-rolling to 90% reduction has been investigated by a combination of X-ray diffraction, optical microscopy, conventional transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) techniques. Multi-pass cold rolling for the Ti–35Nb–5Ta–7Zr alloy includes various localized deformation processes which can result in dislocation tangle, stress-induced ω-phase transformation and deformation-band formation. Deformation-induced amorphization caused by high-density defect accumulation in deformation bands has been identified. By means of TEM and HRTEM observations, distributional, morphological and structural features for deformation bands have been clearly revealed.

Research highlights
► The localized deformation structure of the β-Ti–35Nb–5Ta–7Zr alloy was studied.
► Multi-pass cold rolling of this metastable alloy includes various localized deformation processes.
► We have revealed the structural features for these deformation processes.
► We clearly show that deformation-induced amorphization can take place in deformation bands.