A Fabrication of Low Diffused PtHf Co-Doped Ni-Al Coating on Ni-based Superalloy

Two PtHf co-doped Ni-Al coatings were fabricated by the following steps: first, NiHf layer and Pt layer were electroplated on the substrate, then vacuum annealed at 800 & DEG;C for 5 h; Second, Al layer was deposited via arc ion plating (AIP); Finally, vacuum annealing was proceeded at 1050 & DEG;C for 2 h. The Al contents in PtHf co-doped & gamma;' coating and PtHf co-doped & gamma;'+& beta; coating were about 24 at.% and 42 at.%, respectively. In addition, no topo-logically close-packed (TCP) phases were precipitated in the diffusion affected zone (DAZ) in the PtHf co-doped & gamma;' coating, while many TCP phases were precipitated in the DAZ in the PtHf co-doped & gamma;'+& beta; coating. The interdif-fusion coefficient of Al gradually decreased with the reduction of Al content and the increase of Pt content in coating, consequently suppressing the precipitation of TCP phases.