Finding the energy source for self-propagating high-temperature synthesis production of NiTi shape memory alloy

Our previous works on the synthesis of intermetallics by Self-propagating High-temperature Synthesis revealed strong dependence of microstructure of the products on heating rate. In this paper, the application of various heating regimes and sources was tested in preparation of NiTi shape memory alloy. It was found that high heating rate (approx. over 100 °C min−1) was required to obtain the material with maximized amount of NiTi shape memory phase and no unreacted metals. Heating in electric resistance furnace preheated to the process temperature or induction heating furnace seemed to be promising for this purpose. On the other hand, Spark Plasma Sintering was found to be inapplicable, because the strongest increase of the temperature occurred on the surface of the particles, producing layers of intermetallics that further acted as diffusion barriers.