Microstructure and corrosion behavior of powder metallurgy processed Ti Ni shape memory alloy

Near equi-atomic TiNi shape memory alloy was produced by direct hot isostatic pressing (HIP) of pre-alloyed TiNi powder as well as by reactive HIP of pure Ti and Ni powders. The alloy produced from the elemental powders was further subjected to different heat treatments. The microstructure and the corrosion properties were investigated in the as processed and heat treated conditions. The corrosion behavior was studied in physiological solution simulating human body fluid. The microstructure analysis before and after corrosion was performed, using x-ray diffraction (XRD), optical and scanning electron microscope (SEM). The reactive processed TiNi material water quenched from 1100oC showed the highest microstructural homogenity and the best corrosion resistance. This has been discussed in terms of changes in the microstructural features.