The influence of NI-TI ratio on the reversible austenite-martensite transformation and mechanical properties produced by metal injection moulding

Abstract

This paper highlights the influence of Ni-Ti ratio on the phase constituents, the reversible austenite-martensite transformation and mechanical properties produced by metal injection molding (MIM). The binder system used was mainly palm stearin with minor fraction of polyethylene. Injection moulding was done successfully at 130˚C to form tensile shape samples. It was followed by solvent extraction, thermal debinding at 500°C and subsequently sintered in high vacuum at 1100˚C. The result showed that as the Ni content increased, the fraction of austenite phase also increased owing to greater fraction of transient liquid phase formation during the sintering, thus improved the mechanical tensile properties. However, the reversible austenite to martensite phase transformation temperatures (PTTs) seemed to be broadened with increased Ni content due to formation of metastable R-phase.