Structure and Properties of Porous NiTi Alloy Fabricated by Using New Stearic Acid Pore-Forming Agent

Porous Ni50.8Ti49.2 alloy was prepared using low-temperature decomposable stearic acid particles as pore-forming agent through cascaded powder sintering process.The pore morphology,phase transformation temperature and mechanical properties were studied and compared with those of the alloys fabricated using NH4HCO3 and CO(NH2)2 pore-forming agents.The results show that the porous NiTi alloy fabricated using the stearic acid had nearly spherical,edge round pores and controllable porosity,and its mechanical properties were good and linear superelasticity was stable.Its phase transformation temperatures decreased with the increasing porosity,both the compression strength and shape recovery rate decreased.Compared with the other two pore-forming agents,when the porosity was the same,the porous alloy fabricated by using stearic acid had better mechanical properties,but worse shape memory effect.