Investigation of early stage deformation mechanisms in a metastable β titanium alloy showing combined twinning-induced plasticity and transformation-induced plasticity effects

As expected from the alloy design procedure, combined twinning-induced plasticity and transformation-induced plasticity effects are activated in a metastable beta Ti-12 wt.% Mo alloy. In situ synchrotron X-ray diffraction, electron backscatter diffraction and transmission electron microscopy observations were carried out to investigate the deformation mechanisms and microstructure evolution sequence. In the early deformation stage, primary strain/stress-induced phase transformations (beta -> omega and beta ->alpha(n)) and primary mechanical twinning ({33 2} (1 1 3) and {1 1 2} (1 1 1)) are activated simultaneously. Secondary martensitic phase transformation and secondary mechanical twinning are then triggered in the twinned beta zones. The {3 3 2} (1 1 3) twinning and the subsequent secondary mechanisms dominate the early-stage deformation process. The evolution of the deformation microstructure results in a high strain-hardening rate (similar to GPa), bringing about high tensile strength (similar to GPa) and large uniform elongation (>0.38). (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.