Fabrication of high porous NiTi shape memory alloy by metal injection molding

This paper has investigated the fabrication of porous NiTi shape memory alloy (SMA) by metal injection molding (MIM). A two-step debinding process was used to extract the binder in a molded compact which was produced under an injection pressure of 400 bar, a feedstock temperature of 353 K and a mould temperature of 328 K. The porous NiTi SMA was fabricated by self-propagating high-temperature synthesis (SHS). The results showed that the weight loss of binder reached 98.8% for the solvent debinding. The solvent debinding rate was divided into three stages with time. The microstructure of porous NiTi alloy from molded compact and pressed compact was observed by scanning election microscope (SEM) and the X-ray diffraction (XRD) method was used to analyze the phase of the porous NiTi alloy. It was found that both the porosity and the pores size for the molded compact were much higher than those for the pressed compact. The B2 (NiTi) and B19′ (NiTi) phases were predominantly present in the specimen.