Characterization of porous, net-shaped NiTi alloy regarding its damping and energy-absorbing capacity

Porous NiTi alloys are highly attractive for energy absorbers, damping devices and biomedical implants. In the present work, metal injection moulding (MIM) in combination with the application of a suitable space holder material was used for the production of NiTi parts with well defined pore sizes and porosities in the range of 30–70 vol.%. For comparing the properties, porous titanium and Ti–6Al–4V samples were prepared in the same manner. of the present work was a detailed investigation of the mechanical properties of porous NiTi to estimate its potential regarding the abovementioned applications. For a Ni-rich NiTi alloy with a porosity of 50 vol.%, fully pronounced pseudoelasticity after 6% compression was demonstrated. An energy dissipation of 1.5 MJ/m3 was measured, which could be directly related to the reversible austenite–martensite phase transformation. At higher deformations, pseudoelasticity becomes more and more superposed by the onset of plastic deformation. Nevertheless, even at deformations of up to 50%, a clearly pronounced amount of pseudoelastic shape recovery still remained. Fatigue of pseudoelasticity was investigated by conducting of up to 230,000 load cycles to 4% compression at a frequency of 1 Hz.