Investigation of the microstructure of platinum-modified aluminide coatings

The high temperature performance of Pt-modified aluminide coatings is directly related to their composition and microstructure. In this work, several of the factors that control such features are investigated on a single crystal Ni base superalloy. It will be shown that the bi-phase PtAl2+(Ni,Pt)Al composition is more prone to occur at higher Pt surface concentrations, lower temperatures and shorter aluminising treatments. The alloying elements also seem to play a role in the achievement of either a single or a bi-phase structure. Finally, the incorporation of different elements to the Pt/Al coatings brings about shifting of the X-ray peaks, which in turn may indicate the presence of residual stresses.