Improving Oxidation Resistance of Low Fe-Si Alloys by Preheating Treatment

Abstract

In this work, attempts have been made to improve the oxidation resistance of Fe-Si alloys with 0.5, 1.0 and 2.0 mass pct Si by a preheating treatment, which was carried out at 1073 K for 24 hours in high purity hydrogen atmosphere. Compared with pure Fe and untreated Fe-Si alloys, the oxidation resistance of the preheated Fe-Si alloys at 673 K in O2 is drastically increased, in the case of 2 mass pct Si by two orders of magnitude. The improvement is attributed to a uniform, dense and continuous 25 nm pure SiO2 layer formed on the alloy surface during the preheating treatment in hydrogen atmosphere hindering the diffusion of Fe and O.