Plasma Sprayed NiAl Intermetallic Coating Produced with Mechanically Alloyed Powder

In the present research, mechanically alloyed Ni-AI powder was utilized to develop plasma sprayed coatings, and the effect of the spray distance and heat treatment on the phases, microstructure, and hardness of the coatings were examined. Coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and through microhardness measurements. Although mechanically alloyed Ni-AI powder showed no intermetallic phases, the coatings did. Different spray distances from 5 to 19 cm were employed for plasma spray and the specimens were heat treated at different temperatures, then the amount of oxides, porosity and hardness of the coatings were changed according to the spray condition. The thermal energy of the plasma spray caused the formation of NiAl phases while particles flew to the substrate or after that. Extreme increase in heat treatment temperature and spray distance resulted in oxidation and reduction in the quality of the coating. Furthermore, the best spray distance and heat treatment temperature to gain the NiAl intermetallic coating were established.