The Pd+Rh modified aluminide coating were deposited on nickel and CMSX-4
nickel superalloy. The Pd layer (2.5 ?m thick) with next Rh layer (0.5 ?m
thick) were electroplated on both nickel and CMSX-4. The aluminizing of the
substrates with Pd+Rh layers were performed by the CVD method. Two zones
(outer and interdiffusion) were observed on both coatings. The palladium
doped ?-NiAl phase formed in the outer zones and palladium and rhodium doped
?-NiAl phase was formed at the outer/interdiffusion zone border of both
coatings. The ??-Ni3Al phase and ?-Co7Mo6 precipitates in the ?-NiAl matrix
were found in the interdiffusion zone on nickel and CMSX-4 superalloy
respectively. The simultaneous usage of Pd and Rh in the aluminide coating
slowed their oxidation rate, moreover the Pd+Rh co-doping is more efficient
than Pd+Hf in reducing the oxidation rate of aluminide coating on CMSX-4
superalloy.