Microstructure and properties of NiTi foams with 69% porosity

Ni50.5Ti49.5 foam with 69% porosity was fabricated by sintering elemental Ni, Ti powder compact containing NaCl as space-holder. A layer-by-layer method was used to achieve a homogeneous distribution of Ni, Ti and NaCl powders. Complete removal of NaCl space holders was realized by evaporation of NaCl at high temperature under a vacuum atmosphere, leading to a one-step creation of the foams. The damping capacity (tan delta) of the foam at austenite and martensite states is 0.031 and 0.044, respectively. The maximum strain increases from 7.6% in the sintered state to 25% after aging treatment due to the spheroidization of Ni3Ti and the smooth of the struts. So the aged Ni50.5Ti49.5 foams may act as potential candidate materials for bone implant and energy absorption applications.