Microwave ignited Combustion synthesis of intermetallic compounds, modelling and experimental results

The process of Combustion synthesis (CS) is based on the highly exothermic reaction by reactants, which, if properly ignited, spontaneously turn into products. The aim of this work is to study the CS of β-NiAl formed starting from Ni and Al (1:1 at. %) powders activated by microwaves at 2.45 GHz. Numerical simulation is used to obtain data otherwise difficult to be measured experimentally and to develop a predictive model of microwave ignited and sustained CS of metal powder compacts. The simulation couples an electro-thermal model with a chemical model, required to study the exothermic reaction between powders. A simplify model was obtained and validated, neglecting volume changes, to study compositional and temperature change and reaction kinetics during the CS. It allowed to demonstrate how microwave application, during and after, synthesis could control the cooling rate of products and hence the microstructure of the newly formed intermetallics.