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Indexed by:会议论文

Date of Publication:2008-01-01

Included Journals:EI、CPCI-S

Volume:373-374

Page Number:204-207

Key Words:nickel-based superalloys; simple aluminized; silicon-aluminized; microstructure; formation mechanism

Abstract:Aluminized coatings prepared on nickel-based superalloys can provide good protection against high temperature oxidation and hot corrosion. This study investigated the simple aluminized and silicon-aluminized coatings on nickel-based superalloy K4104. The simple aluminized coating was prepared by pack cementation and the Al-Si coating was prepared by slurry aluminizing, respectively. The microstructure of simple aluminized and Al-Si coatings was analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). And the formation mechanism of simple aluminized and Al-Si coatings was discussed. The results showed that the simple aluminized coating was about 49 um thick and consisted of three layers. The outer layer mainly consisted of Al-rich beta-NiAl. The intermediate layer consisted of Ni-rich beta-NiAl and Cr-rich. The inner diffusion layer consisted of Cr-rich and gamma'-Ni3Al. The microstructure of Al-Si coating showed that the coating was about 70 um thick and consisted of five layers. The Al-Si coating consisted of CrxSiy, Al-rich beta-NiAl, Ni-rich beta-NiAl, Cr-rich and gamma'-Ni3Al. The microstructure of simple aluminized coating was compared with that of Al-Si coating in order to find out the effect of Si. Owing to the effect of Si, there was a Transition layer in Al-Si coating. The Al-Si coating was thicker than simple aluminized coating. The declining trend of the aluminum concentration in the Al-Si coating was smoother than that of the simple aluminized coating.