材料期刊网

A (Ni, Pd) Al coating has been prepared by low-pressure pack cementation on the nickel-base superalloy IN738 with a preplating of Pd-20 wt.% Ni alloy. The coating consists mainly of a single phase of beta-Pd(Ni) Al in the outer part and beta-Ni(Pd) Al in the inner part. The oxidation behavior of the (Ni, Pd) Al coating at 900-1100degreesC was studied by TGA, XRD, and SEM/EDS. Results show that the transformation of theta- to alpha-Al2O3 is more rapid on the (Ni, Pd) Al coating than that on a simple NiAl coating. The addition of Pd to the aluminide coating facilitates the transformation of theta- to alpha-Al2O3 of the oxide scale formed and accelerates the diffusion of Ti from the substrate to the coating surface simultaneously.