Effects of Electropulsing Treatment On Shape Memory and Superelastic Properties of NiTi Shape Memory Alloy

The effect of electropulsing treatment (EPT) on shape memory behaviours of NiTi shape memory alloy was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) measurement, differential scanning calorimetry (DSC) thermal analysis and three points bending test. The time of electropulsing treatment was 8 seconds. SEM was used to examine the changes of the microstructure before and after the EPT. Less surface oxide was observed on all specimens. NiTi (B2) and NiTi (B19’) were found to be the dominant phases in all EP treated specimens with different pulse durations. The austenitic finish temperature (A_f) and its transformation energy as well as amount of martensite were increased with increasing the pulse duration during EPT. Furthermore, the three points bending results showed that the EPT is an effective way to enhance the superelasticity of NiTi shape memory alloy.