Various stages in stress–strain curve of Ti–Al–Nb alloys undergoing SIMT

Ti–Al–Nb alloys in the present range of composition were found to exhibit a typical four-stage behaviour observed in alloys undergoing stress-induced martensitic transformation (SIMT) in β as well as α2–β heat-treated condition. Intermittent unloading–reloading during tensile test was used to measure the apparent modulus at regular strain intervals. This coupled with the observation of microstructure of the samples from tensile tests interrupted at each of the four stages was used to identify the operative mechanism of each stage.