Lightweight and Highly Porous Ni-Ti Alloy Foams Synthesized by Powder Metallurgy using NaCl as Space Holder

Lightweight Ni-Ti alloy foam has received immense attention as a promising material for sensors, actuators, dampers, biomedical implants, and energy absorption applications due to their outstanding properties including low density, high surface area, corrosion resistance and excellent mechanical strength. In the present study, we developed Ni (50)-Ti (50) alloy foams with varying porosities using NaCl as a space holder. The cold compacted mixture of NiTi alloy powder, NaCl granules, and 2 wt% polyvinyl alcohol (PVA) solutions are mixed uniformly in a globe box for 8 hrs. Sintering is carried out in two stages: firstly, at 900 oC for 2 hrs and then at 1100 oC for two hrs. During sintering, NaCl gets melted and removed from the foams. The Ni-Ti alloy foams exhibit an excellent compressive strength of 48 MPa at a relative density (ρrd) of 0.45. It also provides higher plateau stress, greater strain hardening effect, and larger strain recovery. Thus, the lightweight high strength Ni-Ti all