Transition Between Different Oxidation Modes of Binary Fe-Si Alloys at 600-800 in Pure O_2

摘要

The oxidation behavior of three Fe-Si alloys containing approximately 5, 9 and 13 at.% Si has been studied at 600-800 under 1 atm O_2. Fe-5Si and Fe-9Si followed multi-stage parabolic kinetics, while Fe-13Si showed more complex kinetics at all temperatures. The increase in Si content resulted in a transition from the internal oxidation of Si beneath an external scale of iron oxides to the exclusive external formation of silica. The critical contents required for the transitions between the various possible oxidation modes of the binary Fe-Si alloys were calculated and compared with the experimental results. A thermodynamic mechanism for the formation of Fe-rich oxide nodules observed in the oxidation of Fe-5Si and Fe-9Si has been proposed.