Journal of Mining and Metallurgy. Section B: Metallurgy (Jan 2023)

Synergistic effect of Pd+Rh on the microstructure and oxidation resistance of aluminide coatings

  • Zagula-Yavorska M.

DOI
https://doi.org/10.2298/JMMB231017040Z
Journal volume & issue
Vol. 59, no. 3
pp. 465 – 476

Abstract

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The Pd+Rh modified aluminide coatings were deposited on nickel and CMSX-4 nickel superalloy. The Pd layer (2.5 μm thick) and the subsequent Rh layer (0.5 μm thick) were electroplated on both nickel and CMSX-4. The aluminization of the substrates with Pd+Rh layers was carried out using the CVD method. Two zones (outer and interdiffusing) were observed on both coatings. The β-NiAl phase doped in palladium was formed in the outer zones and β-NiAl phase doped with palladium and rhodium was formed at the boundary between the outer and interdiffusion zones of both coatings. The γ’- Ni3Al phase and μ-Co7Mo6 precipitates in the β-NiAl matrix were found in the interdiffusion zone on nickel and CMSX-4 superalloy respectively. The simultaneous use of Pd and Rh in the aluminide coating slowed down their oxidation rate. Moreover, Pd+Rh co-doping is more efficient than Pd+Hf in reducing the oxidation rate of aluminide coating on CMSX-4 superalloy.

Keywords