Engineering the porosity and superelastic behaviors of NiTi alloys prepared by an electro-assisted powder metallurgical route in molten salts

An Electro-Assisted Powder Metallurgical (EPM) route is able to prepare porous NiTi alloys with controllable porosities and pore sizes using nickel (Ni) and titanium (Ti) powders at a temperature ranging from 850 to 950 degrees C. Ammonium hydrogen carbonate (NH4HCO3) was used as a sacrificial space holder to tailor the porosity and pore size of the NiTi alloy and its properties, i.e., elastic modulus, phase transformation temperature, shape memory effect, and superelasticity. By optimizing the synthesis temperature and content of the sacrificial space holder (0-30%), the porosity (41-75%), pore size (22 -174 mu m), elastic modulus (4.77-0.87 GPa) and the recovery strain (>2%) of the EPM-NiTi can meet or are close to the standard of natural bone (porosity: 30%-80%, pore size: 100-600 mu m, cancellous modulus: < 3 GPa, recovery strain: > 2%). Therefore, the EPM route is promising to prepare porous Ti-based alloys for implants. (C) 2019 Elsevier B.V. All rights reserved.