Microstructure and Pore Structure of Porous NiTi Shape Memory Alloys Prepared by Self-propagating High-temperature Synthesis

Using nickel powders and titanium powders as raw materials,porous NiTi shape memory alloys (SMA) were prepared by using self-propagating high temperature synthesis (SHS) technique.The influences of parameters such as the sample pressure,nickel content and titanium powder size on pore size,pore uniformity and microstructure were studied.The results show that the NiTi alloy synthesized by SHS technique had spiral and laminar structure.The samples pressed between 100-200 MPa had uniform pores and were ideal 3-D connection structure.With nickel mass fraction of 40% the pore distribution and three-dimensional interconnectability were ideal.When the granularity of titanium powers was large,liquid phase and impurity NiTi2,Ni3Ti droplets turned up,and the granularity between 50-100 μm was preferable.