Investigation on Crack Tip Transformation in NiTi Alloys: Effect of the Temperature

The effect of the temperature on crack tip transformation in Nickel–Titanium (NiTi) shape memory alloys was analyzed in this work by means of experimental and analytical approaches. In particular, single edge crack specimens were analyzed for two different values of the testing temperature in the pseudoelastic regime of the alloy, i.e., T = 298 K and T = 338 K. The thermal-dependent phase transition mechanisms occurring at the crack tip region were studied by analyzing data obtained from digital image correlation as well as by nanoindentation experiments performed near the crack tip. Finally, experimental results were compared with predictions of a recent analytical model. Results revealed that an increase in temperature causes a decrease of the phase transformation zone and that both the techniques are well suitable in capturing the thermal effect on the phase transformation mechanisms near the crack tip. © 2015, ASM International.