Porous NiTi shape memory alloys prepared with hydride hydrogenated (HDH) titanium powder generally have inferior load-bearing properties and recoverable strain. In this study, porous NiTi alloys with high strength and stabilized cyclic properties are prepared by homogenizing sintering at high temperature (1250 °C) under high vacuum (10-4 Pa) using NaCl as space-holder. The microstructure, phase transformation, mechanical properties and cytotoxicity are investigated with different porosities. It shows that the porosity and pore size of the samples increased with the increase of NaCl addition, while the oxygen content increased slightly. Spontaneous formation of Ni4Ti3 nano-precipitates without heat treatment are observed. The size of precipitation grows as the increase of oxygen content. The martensitic transformation showed multiple peaks, attributed to the inhomogeneous distribution of the precipitation. The compressive strength of porous NiTi alloys with 14% ~ 37% porosity is approximately 1236 ~ 1600 MPa. Shape recovery rate after compressive loading-unloading at 8% strain exceeds 99%. In constant stress-controlled compression cyclic tests, all samples exhibit excellent cyclic stability. The outstanding biocompatibility is also presented in cytotoxicity test.
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