Fabrication of cellular shape memory alloy materials by reactive eutectic brazing using niobium

A novel metal-joining process is described that exploits interfacial reactions between nitinol and pure niobium to produce a reactive eutectic liquid that readily creates a robust metallurgical bond between nitinol and itself. With this new reactive-brazing process we have been able to create prototypes of superelastic cellular honeycomb topologies from conventional nitinol precursor materials such as tubes and corrugated sheets. These have been found to display excellent isothermal shape-recovery and have high specific strength, low relative density, and extremely high resilience. The method will allow realization of complex space-frames, honeycomb sandwich panels, and other sparse built-up thermally active multifunctional nitinol structures. The braze material is corrosion-resistant, machinable, biocompatible, and has good osteoconductivity, potentially enabling a variety of compliant superelastic implant and bone-replacement materials unobtainable by any other means. (c) 2006 Published by Elsevier B.V.