Reversible displacive transformation with continuous transition interface in a metastable β titanium alloy

Abstract Super-elasticity and shape memory of materials are typically associated with reversible phase transformations. The reversible phase transformations and their governing factors thus have long been research interests of materials scientists and physicists. Here, a novel reversible ω transformation has been observed in a metastable β-Ti alloy during tensile deformation with in situ aberration corrected transmission electron microscopy. We reveal that the reversible transformation is attributed to a trigonal crystal structure of the ω phase. Moreover, continuous transition interfaces with no interfacial defects are formed between the ω and β phases, and they contribute essentially to the occurrence of the reverse transformation. This reversible transformation has great potential for developing super-elasticity and shape memory in materials.