Selective oxidation of ternary Fe-Mn-Si alloys during annealing process

Abstract

Selective oxidation of Fe2MnxSi alloys with various Si contents annealed in a gas mixture of H2/H2O (p(O2) = 6.5×10−25 bar at 700 °C) for 2 h was investigated. The oxidation kinetics of all the alloys followed linear growth, indicating that most likely oxygen uptake was the rate-determining step. The addition of Si into Fe2Mn eliminated the formation of the ridge-like MnO at the surface, mainly on the grain boundaries, but significantly accelerated the internal oxidation especially along grain boundaries. The effects of Si on the external and internal oxidation including the morphology, distribution and chemistry of the oxides are discussed.