Microwave-assisted combustion synthesis of NiAl intermetallics in a single mode applicator: Modeling and optimisation

The microwave-assisted combustion synthesis of NiAl intermetallics in a single mode applicator has been simulated numerically and performed with the aim of achieving the highest yields, energy efficiency and process reproducibility. The electromagnetic field modeling of the microwave system allowed to chose the proper experimental set-up and the materials more suitable for the application, minimising the reflected power and the risks of arcing. In all the experimental conditions tested, conversions of 3–5 g 1:1 atomic ratio Ni and Al powder compacts into NiAl ranged from 98.7% to 100%, requiring from 30 to 180 s with power from 500 to 1500 W. The optimisation procedure allowed to determine and quantify the effects of the main process variables on the ignition time, the NiAl yields and the specific energy consumption, leading to a fast, reproducible and cost-effective process of microwave-assisted combustion synthesis of NiAl intermetallics.