材料期刊网

Micro-crystalline beta -FeAl+Zr coatings on cast beta -FeAl and 304S stainless steel substrates were produced with unbalanced magnetron sputter deposition technique. Isothermal oxidation in pure O-2 and a cyclic oxidation test in ambient air at 1000 degreesC were carried out to assess the oxidation resistance of the coatings. The spallation resistance of the oxide scale formed on the coatings was superior compared with the uncoated alloys. After the oxidation in O-2, large voids at the cast FeAl/oxide interface were observed; while no obvious voids were found at the coating/oxide interface. Outward Al diffusion and S interfacial segregation were considered as the reasons for the formation of the voids. Recrystallization and grain growth of the coating was believed to play an important role in improving the spallation resistance. The chemical compatability of the coating with 304S stainless steer substrate was also discussed.