Properties of Ti-Nb-Zr shape memory alloy fabricated by mechanical alloying and hot isotatic pressing

Ni-free Ti-based shape memory alloys (SMAs) are becoming increasingly attractive for biomedical application because they are non-toxic and bio-compatible. In the past decades, systematic researches have been focused on studying TiNb-based SMAs. Recently, detailed investigations have been focused on the shape memory effect of TiNb-based alloys by adding ternary elements, such as Mo, Sn, Zr, etc. However, only arc melting or induction melting methods, with subsequent hot or cold rolling, were used to fabricate these Ni-free SMAs. There is no work related to powder metallurgy and porous structures. This study is to focus on the fabrication and characterization of a ternary Ti-Nb-Zr SMA produced from elemental powders by means of mechanical alloying (MA) and hot isostatic pressing (HIP). It is found that the alloy shows homogenous composition distribution and an average grain size of 50mm after HIP followed by subsequent annealing. X-ray diffraction and optical microscopy reveal the presence of the martensitic phase. Differential scanning calorimetry thermal analysis was further used to determine the phase transformation temperatures. The alloy also exhibits good mechanical properties, such as superior superelasticity as well as high compressive strength.