Laser ignition in Self-propagating High temperature Synthesis of porous NiTinol Shape Memory Alloy

Self-propagating High temperature Synthesis (SHS) is a challenging method for producing porous near net-shape materials. Starting from pure metallic powders several compounds can be fast synthesized. Among promising porous structured materials for biomedical applications NiTinol Shape Memory Alloy can be suitable for their peculiar properties, like shape memory effect or pseudo-elasticity, high biocompatibility and lightness. In the present work SHS process on Ni and Ti elemental powders, ignited by a laser beam, was studied. The effect of main laser parameters (laser power and exposition time) was studied on porosity, microstructure and martensitic transformation temperatures. Samples with porosity in the range 42-48% were produced; NiTi matrix and other secondary phases, like NiTi2, Ni3Ti and Ni4Ti3 were detected. No dependence of microstructure and transformation temperatures with the process parameters was found in the investigated range.