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This study deals with the microstructure of a Pt modified aluminide coating obtained with an aluminizing treatment without prior Pt diffusion. IN100 (polycrystalline) and AM1 (single crystal) superalloys have been used as substrates and coated by an Aluminizing Phase Vapor Snecma (APVS®) low activity treatment developed by Snecma-Services. By using the Fisher experiment design method, we have shown that three types of microstructures can be obtained, depending on the type of the donor: a monophased (Ni, Pt)Al, a first two-phased PtAl2/NiAl, or a second two-phased PtAl2/NiAl with a continuous PtAl2 layer. Moreover, the presence of platinum at the surface allows a better incorporation of aluminum by comparing the aluminizing treatment with prior Pt diffusion. Finally, stability of the newly observed two-phase structure PtAl2/NiAl with a continuous PtAl2 layer at the surface has been investigated. [Copyright &y& Elsevier]

The in-depth microstructure changes in nickel-based superalloy due to prior Pt diffusion treatment have been analyzed using complementary X-ray methods. X-Ray diffraction shows the presence of a three-phase system in the entire treated thickness for thick Pt coatings (10 μm). Surface probing by X-ray absorption spectroscopy reveals the presence of a Pt-based phase at the top surface. For thinner Pt coatings (5 μm), X-ray diffraction and absorption techniques reveal a homogeneous in-depth microstructure associated with the γ/γ′ Ni-based superalloy phases. Results obtained for these two thickness values are well correlated with in-depth Pt concentration profiles determined by energy-dispersive X-ray analysis (EDX). [Copyright &y& Elsevier]