Dispersion-strengthened modified MCrAlY coatings produced by reactive deposition

The detonation gun coating process was used to change controllably the microstructure of MCrAlY powders to produce either oxide- or carbide-dispersed overlay coatings. Based on analyzed oxygen and carbon contents, and the starting powder composition, the equilibrium phases of the coatings were calculated. From this, the desired MCrAlY matrix composition was calculated for various hypothetical powder compositions. In one example, the matrix aluminium was designed to be about 14 wt.%, by compensating for the alumina formed by the reactive coating process. In another case, a strong carbide formal was added to compensate for some of the Cr carbide formation, based on the equilibrium calculation. The powders and coatings were made, and the coatings heat treated for phase analysis and oxidation testing. Results of this investigation demonstrate the benefits associated with oxide or carbide dispersions in MCrAlY coatings processed by reactive deposition.