A fabrication of low diffused PtHf co-doped Ni-Al coating on Ni-based superalloy.

• NiPt-Hf layer provided Ni element required to form the coating. • There was no TCP phase precipitation in DAZ for PtHf co-doped γʹ coating. • The thickness of DAZ in PtHf co-doped γʹ+β coating was about 18 μm. • The proportion of β-NiAl in coating increased with the increase of Al layer thickness. 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 ℃ for 5 h; Second, Al layer was deposited via arc ion plating (AIP); Finally, vacuum annealing was proceeded at 1050 ℃ for 2 h. The Al contents in PtHf co-doped γʹ coating and PtHf co-doped γʹ+β coating were about 24 at.% and 42 at.%, respectively. In addition, no topologically close-packed (TCP) phases were precipitated in the diffusion affected zone (DAZ) in the PtHf co-doped γʹ coating, while many TCP phases were precipitated in the DAZ in the PtHf co-doped γʹ+β coating. The interdiffusion 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. [ABSTRACT FROM AUTHOR]