We investigated the combination effect of plastic deformation and phase transformation on the evolution
of microstructure and property of NiTi alloy. Samples of Ni50.9Ti49.1 alloy were deformed by cold
rolling to different strains/thickness reductions (4%e56%). X-ray diffraction, transmission electronic
microscopy (TEM) and microhardness measurements were applied for characterization of the microstructure
and property of the cold-rolled samples. Experimental results indicated the non-monotonic
variations of microstructure parameters and mechanical property with strain, indicating the different
processes in microstructure and property evolution of NiTi subjected to cold rolling. TEM observations
further showed the dominating mechanisms of microstructure evolution at different strain levels,
leading to the gradual reduction of grain size of NiTi to the nanoscale by cold rolling. The results were
discussed and related to deformation of martensite, forward and reverse martensitic transformations and
dynamic recrystallization. The present study provided experimental evidences for the enhanced formation
of nanograins in NiTi by plastic deformation coupled with phase transformation