Oxidation behaviors of Ni-Cr-Al superalloy foams at 1 000 °C in air
The oxidation behaviors of Ni-16Cr-xAl (x=4.5%, 9.0%, mass fraction) superalloy foams in air at 1 000 °C were investigated. The effects of Al content on the resistance to high temperature oxidation were examined. The oxidation mechanisms of the foams were discussed. The results show that the resistance to the oxidation of the Ni-16Cr-xAl based alloy at 1 000 °C increases with the content of Al increasing from 4.5% to 9.0%. Complex oxide products are formed on the surface of the superalloy foams after the oxidation. Cr2O3 and Al2O3 are the predominant oxides for the scales of the foams with 4.5% Al and 9% Al, respectively. Excellent high temperature oxidation resistance and superior pore conformation stability for the Ni-16Cr-xAl based superalloy foam with 9% Al can be mainly attributed to the formation of relatively continuous and protective Al2O3 oxides on the surface of the foam.