Structure and high temperature hot corrosion of palladium modified aluminide coatings on nickel-base superalloy

Pd modified aluminide coatings on casting nickel based superalloy M38 were developed by conventional pack aluminizing technology.Pd 20wt%Ni was predeposited before aluminizing.The structure of coatings was thoroughly analyzed.A major difference between Pt and Pd modified aluminide coatings resides in the fact that the Pd zone is single phased and the constitutive phase is β (Pd X,Ni 1-X )Al.The corrosion resistance of Pd Ni Al coatings was more 3.5 times in Na 2SO 4 melt,and obviously better in Na 2SO 4+NaCl melt than conventional aluminide coating at 1173K.Pd Ni Al coatings behave at least as well as commercial Pt Al coatings under the same testing conditions.The hot corrosion mechanism was preliminary discussed.