Dissolution–precipitation mechanism of self-propagating high-temperature synthesis of mononickel aluminide

A combustion front quenching method (CFQM) was used for investigating the mechanism of self-propagating high-temperature synthesis of NiAl from Ni and Al powders. The microstructural evolution in the quenched sample was observed with scanning electron microscopy (SEM) and analyzed with energy dispersive X-ray (EDX) spectrometry. In addition, the combustion temperature and rate were measured, and the phase constituent of the final product was inspected by X-ray diffraction (XRD). Based on the experimental results, a dissolution–precipitation mechanism of the combustion synthesis of NiAl was proposed, and a model corresponding to this mechanism was drawn. Also, previous results were explained, and incompleteness of the synthesis was found to be related to the usage of coarse reactant powders.