An Electro-Assisted Powder Metallurgical Route for the Preparation of Porous Ti and NiTi in Molten CaCl₂

Molten salts can provide a high-temperature and oxygen-water-free environment, and the electrochemical polarization is able to reduce the oxide scale on the surface of Ti and Ni particles in molten salts and, thereby, enhance the sintering and accelerating atom diffusion between Ti and Ni. Thus, an electro-assisted powder metallurgical (EPM) approach was developed to prepare porous Ti and NiTi from metal powders in molten salts, where the porous pellet cathode made of the mixture of Ni and Ti powders is electrochemically polarized to facilitate the generation of the porous Ti and NiTi at a temperature lower than 1000 °C. The electrolytic product obtained under a cell voltage of 3 V for 12 hours is nearly pure NiTi with a tiny amount of undesired Ni₃Ti and NiTi₂ phases. Overall, the EPM route could be a straightforward and general way to prepare porous Ti and Ti-alloys for implants and other applications.