Fabrication and Wear Behavior of Nano-Al2O3 Dispersed NiTi-Based Composites by Mechanical Alloying and Hot Isostatic Pressing

NiTi matrix composites reinforced with Al2O3 nanoparticles have been synthesized by mechanical alloying of Ni and Ti in the presence of Al2O3 nanoparticles and consolidated by hot isostatic pressing (HIP). Microstructural studies revealed that the sintered composites have a complex phase structure including B2 and B19’ NiTi and Ni-rich (Ni3Ti) and Ti-rich (NiTi2) phases. Nanoindentation test results demonstrated that both hardness and elastic modulus were considerably increased in the composite samples in comparison with pure NiTi, while the pseudoelasticity was not significantly reduced. The wear test results confirmed the improved wear performance of NiTi matrix after the addition of nanoparticles under both low and high loads can be mainly attributed to superior mechanical properties combined with pseudoelasticity effect of the composite samples.