Irradiation-induced changes of martensitic transformation temperatures in a TiNiNb shape memory alloy

Effects of electron irradiations on the transition behavior of 1123 K annealed Ti44Ni47Nb9 shape memory alloy specimens were studied. The transformation temperatures and the latent heat of phase transformation were measured by differential scanning calorimeter (DSC). The microstructure changes were determined by XRD and TEM. The 1.7 MeV electron irradiation increases the martensitic transformation start temperature, finish temperature, austenite transformation start, finish temperature by ∼20 K. The XRD and TEM observation showed that the volume fraction of β-Nb precipitate increased after electron irradiation, which contributed to the observed changes of the transformation temperatures.