Interdiffusion behavior of Pt-diffused γ+γ′ coatings on Ni-based superalloys

Influence of the superalloy substrate in the synthesis of the Pt-modified aluminide bond coat made by slurry

“…Indeed, for Pt x Al y to form, significant Al contents are requiredat least at very local scale - [27] and this depends on the initial Al con- 247LC than in the SX CMSX-4) and on the annealing conditions. Even so, the uphill diffusion of Al of 22 at.% observed in a 7-μm Pt-plated René N5 after annealing was insufficient to observe the formation of Pt x Al y [28]. However, microstructural differences appeared between both the SX and the DS substrates.…”

Diffusion behaviour of Pt in platinum aluminide coatings during thermal cycles

“…When the diffusion fluxes of Ni and Al were not balanced and there are insufficient vacancy sinks, Kirkendall voids could form. It is possible that these voids then coalesce into large cavities because of thermal stress [5,6].…”

“…Ni diffuses outward from the substrate into the coating. Zhang et al observed a decrease in the Pt content at the Ptdiffused c+c' coating surface from 24 to 18 at.% and a Pt depth of double the original 40 lm thickness after 1 000 h at 1 000 8C [6]. Gleeson and Hayashi suggested that sufficient Pt level (>15 at.%) is necessary for uphill Al diffusion to generate TGO in the c+c' alloys [7,8].…”

OXIDATION RESISTANCE AND MICROSTRUCTURE OF Pt AND PtIr DIFFUSION COATINGS ON Ni BASED SINGLE CRYSTAL SUPERALLOYS BY ELECTROPLATING METHOD

“…However, β-containing coatings suffer from transformation from β to γ'-Ni 3 Al or -Ni solid solutioned phase, which leads to surface rumpling, and interdiffusion between substrates and coatings leads to the formation of intermetallic phases with brittle topologically close-packed (TCP) structure in service, which results in the degradation of coated materials [3]. To overcome such problems, recently, Pt diffusion coatings with the γ+γ' phase microstructure, similar with that of substrate, have been proposed and their oxidation resistance have been reported [4][5][6]. It has been shown that they could reduce the rumpling [5,7,8] and limit or suppress the precipitation of brittle TCP phases [7].…”