Identification of an Al-Ni-O precipitate in combustion-synthesized NiAl

The complete identity of a second-phase precipitate detected by transmissio n electron microscopy in combustion-synthesized NiAl was established. The c rystal structure, including the point group, the space group and the lattic e parameters, was determined by convergent and selected-area electron diffr action techniques. Energy dispersive X-ray spectroscopy was used for the de termination of the chemical composition. Analysis established the phase to be the solid solution of NiO in Al2O3 and presented evidence of the hithert o unreported room-temperature solubility.