Microstructural Characterization and Wear Performance of NiTi-ZrO2 Composites

In this study, NiTi-x wt% monoclinic ZrO2 (x = 0, 5, and 10) samples were fabricated with spark plasma sintering method and the role of zirconia microparticles addition on the microstructure, martensitic transformation, and wear behavior of NiTi-ZrO2 samples was investigated. Microstructural observations using scanning electron microscopy equipped with energy dispersive spectroscopy confirmed the formation of Ti-rich regions in NiTi/zirconia interfaces. The evolution of mismatch stress in the composite samples can increase the dislocation density, especially at the interfacial regions. This facilitates the diffusion of titanium from the matrix which leads to the formation of NiTi2 phase in the composite samples. According to differential scanning calorimetry analysis, the martensitic transformation temperatures of zirconia reinforced samples increases that shows the higher stability of the martensite phase at room temperature. Rietveld refinement analysis also approved this finding. According to wear test results, the wear rate of NiTi sample is 5.74 x 10(-3) mm(3)/N m. However, after the addition of 5 wt% ZrO2, the wear rate decreases to 1.49 x 10(-3) mm(3)/N m which confirms the positive effect of zirconia reinforcements on the wear performance of NiTi-based samples. This improvement can be attributed to a better combination of hardness and pseudoelasticity in this sample.

Automated summary

This study investigated the effects of zirconia microparticles on the microstructure, martensitic transformation, and wear behavior of NiTi-based samples. Results showed that the addition of zirconia can enhance the stability and wear performance of the composite samples.