Characterization of the Microstructural Degradation of Platinum Modified Aluminide Coating

Abstract:

This work presents the degradation mechanism of the platinum modified aluminide diffusion coating of the GTD 111 SC Ni-base superalloy turbine blades after 16000 h of exposition at different thermal cycles (critical heating temperatures reported ~1000°C and 1120°C). The initial coating condition and the evolution of degradation were characterized applying conventional microscopy and backscatter scanning electron microscopy. The initial microstructure condition consisted of a two phase coating (intermetallics PtAl₂ dispersed in a matrix β-(Ni,Pt)Al). The major microstructure degradation was associated with: intermediate and interdiffusion zones growing, partial transformation of β-(Ni,Pt)Al to γ´-Ni₃Al, and the dissolution of the intermetallic PtAl₂ resulting in a more brittle single phase β-(Ni,Pt)Al coating. The degradation facilitates spallation and crack initiation, resulting in the loss of the coating and by consequence the blade failure.

• Periodical: Materials Science Forum (Volume 755)
• Pages: 29-38
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.755.29
• Online since: April 2013
• Authors: M.A. González, D.I. Martínez, C.T. Saucedo, I. Guzmán, J.C. Díaz
• Keywords: Aluminide, Coating, Intermetallic, Oxide, Platinum, Superalloy

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