Ongoing research is presented on processing of NiTi-based shape memory alloy (SMA) foams. The aim is to demonstrate a new class of materials that combine the advantages of light-weight metallic foams with the strain recovery and energy-dissipation capability of SMAs. There are a number of potential novel structural and biomedical applications that could be enabled by the unusual passive and active properties of such a material. This paper presents initial results on our attempt to fabricate functional prototype specimens using a polymeric foam precursor and a powder metallurgy process to produce NiTi foams with user-selected topology and relative density. It is shown that open-cell NiTi foams with relative density less than 5% can be produced with this technique. While definite martensitic transformational behavior has been achieved in the prototypes, the quality of the foams are found to be sensitive to the sintering temperature, the binder system employed, and the levels of interstitial contamination. Further work is needed before good superelastic and shape-memory properties can be demonstrated. Nevertheless, the current technique appears promising, since the method is capable of producing NiTi foam with a more regular structure and at a relative density nearly an order of magnitude less than other techniques currently used to produce porous NiTi.

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