Combustion synthesis of NiAl/Al2O3 composites by induction heating

Combustion synthesis of NiAl requires the combustion reaction to be ignited and fully controlled to maintain the geometry of the compressed parts. This paper describes a new ignition process using induction heating and investigates the effect of Al2O3 on both the combustion synthesis process and the performance of the synthesized products. A high frequency induction heater was used to ignite the synthesis reaction. During synthesis the temperature profiles were measured with infrared thermometers to monitor the reaction process and X-ray Diffraction was used to investigate the phase transformation. The results show that single phase NiAl can be produced by this new process regardless of the addition of Al2O3. However, the addition of Al2O3 was found to have a significant effect on heating rates, combustion behaviour and properties of the synthesized products. Additionally, there is a critical concentration for Al2O3 above which the compacts cannot be ignited by induction heating. Mechanical properties of the products were tested to evaluate the performance of the synthesized composites.