Crystallization behavior in severely cold-drawn Ti50Ni47Fe3 wire

The microstructures and crystallization behavior of Ti–47 at% Ni–3 at% Fe shape memory alloy wire under the condition of severe cold drawing at room temperature and different post-deformation annealing processes were intensively investigated using transmission electron microscope (TEM) and differential scanning calorimetry (DSC). It is indicated that the amorphous phase is dominant in the Ti₅₀Ni₄₇Fe₃ wire after the cold drawing of 78 % areal reduction. The critical temperature for recrystalization is determined at about 300 °C. The average grain size grows from 7 up to 125 nm when annealing temperature rises from 300 to 500 °C. Post-deformation annealing process exerts significant influence on the crystallization temperature which climbs up with the increase of annealing temperature.