INTERDIFFUSION OF THE ALUMINIZED AND PT-ALUMINIZED COATINGS ON MAR-M247 SUPERALLOY

Investigations have been performed into the interdiffusion behaviours of both aluminized and Pt-aluminized coatings on MAR-M247 superalloy. The interdiffusion leads to the formation of the NiAl phase for the aluminized coating, while the PtAl2 phase was identified in addition to the NiAl phase for the Pt-aluminized coating. On the basis of elemental analysis, with movement at different positions of the interdiffusion zone and location of the original interface, it was concluded that Ni diffuses outwards for the aluminized coating in the present study. For the case of the Pt-aluminized coating, Pt behaves as the diffusion media which enhances the outwards diffusion of Ni and the inward diffusion of Al to form the NiAl and PtAl2 phases. Co is the major alloying element which diffuses outwards and dissolves in the surface aluminide phases.