Effect Of Rare Earth Element Y And Micro-crystallization On High Temperature Oxidation Behavior Of Fe-cu-ai Alloy

The addition of rare earth element and micro-crystallization play a crucial roleon the high temperature oxidation resistance of multicomponent superalloys.However, the oxidation mechanism of the two factors is very complex and needs tobe clarified systemly. The aim of the present work is to examine the effects of rareearth element yttrium and micro-crystallization on high temperature oxidationbehavior of Fe-15Cu-5Al，Fe-15Cu-8Al, and Fe-15Cu-10Al, which is of greatimportance for establishing the basic high temperature oxidation theory ofmulticomponent superalloys and for the development of advanced superalloys.The oxidation behavior of Fe-15Cu-5Al alloy containing about0.1at.%and0.3at.%yttrium and that of Fe-15Cu-5Al-0.3Y microcrystalline coating were studied at700and800℃under1atm O2. Rare earth element yttrium accelerated theoxidation of the alloy, due to the rapid diffusion and oxidation of Fe promoted by thepresence of Y. Fe-15Cu-5Al-0.3Y microcrystalline coating produced by magnetronsputtering had typical columnar structure, and its oxidation rate was very fast. Thecombined effects of rare earth element yttrium and micro-crystallization, greatlypromoted the selective external oxidation of Fe, and accelerated the oxidation of thealloy.The oxidation behavior of Fe-15Cu-8Al alloy containing about0.1at.%and0.3at.%yttrium and that of Fe-15Cu-8Al microcrystalline coating were studied at700and800℃under1atm O2. With the addition of0.1at.%yttrium, a continuousAl2O3layer formed on the alloy, which inhibited the oxidation of the alloyeffectively. The addition of0.3at.%yttrium increase the oxidation rate of the alloy.Micro-crystallization promoted the selective oxidation of Fe, resulting in the seriousoxidion of Fe-15Cu-8Al alloy.The oxidation behavior of Fe-15Cu-10Al alloy containing about0.1at.%and0.3at.%yttrium was studied at700and800℃under1atm O2. The protective Al2O3layer can not formed due to the addition of0.1at.%and0.3at.%Y. As a result of theaddition of Y, the oxidation of Fe was promoted greatly.