Investigation on the Presence of Titanium Oxide particles Effect in Preventing the Growth of NiTi Granules in the Sintering Process

Grain growth during sintering of nanomaterial is one of the main drawback is this process. Since the nanomaterials maintain their unique performance as long as their size dos not exceed a specific size range, various strategies, including the addition of oxide particles, are adopted to prevent this phenomenon and to slow down grain growth. In this research, titanium oxide particles were used to prevent the growth of NiTi nanostructured alloy grains during sintering operations due to their suitable thermal stability with amount of 10 wt.%. The effect of titanium oxide particles was investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses. For this purpose, two groups of samples including with and without presence of titanium oxide were prepared and studied. The results of kinetic analysis on both sample groups showed that grain growth occurred after the process, in the presence of this oxide, up to twice the initial size and before sintering. But the growth rate in the absence of titanium oxide increased up to five times. The reason for this is the amount of activation energy required for grain growth. This energy was 31.85 kJ in the sample without titanium oxide and 47.96 kJ in the sample with the presence of 10% of this oxide. Also, based on DSC data, the barrier energy were calculated as 9.93 and 7.75 kJ, and the grain growth activation energy were calculated as 13.4 and 14.4 kJ, for the samples with out and with titanium oxide respectively.