Improving cyclic oxidation resistance of Ni₃Al-based single crystal superalloy with low-diffusion platinum-modified aluminide coating

H.Liu^1,2，M.M.Xu^1,2，S.Li^1,2，Z.B.Bao¹，S.L.Zhu¹，F.H.Wang³

1. Institute of Metal Research, Chinese Academy of Sciences2. School of Materials Science and Engineering, University of Science and Technology of China3. Shenyang National Laboratory for Materials Science, Northeastern University

摘 要：A low-diffusion Ni Re Pt Al coating（（Ni,Pt）Al outer layer in addition to a Re-rich diffusion barrier layer） was prepared on a Ni3 Al-base single crystal（SC） superalloy via electroplating and gaseous aluminizing treatments, wherein the electroplating procedures consisted of the composite deposition of Ni-Re followed by electroplating of Pt. In order to perform a comparison with conventional Ni Al and（Ni,Pt）Al coatings, the cyclic oxidation performance of the Ni Re Pt Al coating was evaluated at 1100 and 1150?C. We observed that the oxidation resistance of the Ni Re Pt Al coating was significantly improved by the greater presence of the residual β-Ni Al phase in the outer layer and the lesser outward-diffusion of Mo from the substrate.In addition, the coating with the Re-rich diffusion barrier demonstrated a lower extent of interdiffusion into the substrate, where the thickness of the second reaction zone（SRZ） in the substrate alloy decreased by 25 %. The mechanisms responsible for improving the oxidation resistance and decreasing the extent of SRZ formation are discussed, in which a particular attention is paid to the inhibition of the outward diffusion of Mo by the Re-based diffusion barrier.

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