Investigation of sintering time effect on the structural and mechanical properties of Ni-Ti alloy

In this study nitinol alloys were sintered at 1050 °C for different times of 1, 2, 4, 7 and 10 hours. Then they were investigated by metallographic analysis, X-ray diffraction (XRD) analysis, compression and differential scanning calorimetry (DSC) tests. Structural studies revealed that NiTi become the dominant phase and Ni3Ti peaks intensity decreases by increasing time, but the possibility of complete elimination of them is so weak. Compression investigations and DSC measurements showed that due to the presence of porosity, austenitic-martensitic transformation behavior won’t be seen in the samples and by increasing sintering time from 1 h to 10 h, Young’s modulus increases from 3.64 Gpa to 4.58 Gpa. It was also seen that by increasing loading-unloading cycles from one cycle to four cycles, residual strains significantly reduce.