Effect of interactions between Fe–Al alloy and MgO-based refractory on the generation of MgO·Al 2 O 3 spinel

Abstract

In the present study, interactions between Fe-2.1 wt-%Al and Fe-5.1 wt-%Al alloys and different tundish refractories, and a spinel generation in the Fe–Al alloys were investigated in laboratory experiments at 1550°C in an alumina crucible using a high-frequency induction furnace. The results indicated that the formation of a spinel layer at the interface was owing to both the oxidation–reduction reactions and the phase transformation at the interface according to initial phases in refractories. The thickness of the interface layer increased with increasing the content of the [Al] in Fe–Al alloys, the SiO₂ content in the refractory and the immersion time, however, the [Al] content was a dominant factor. Both experimental results and thermodynamic calculations concluded that MgO·Al₂O₃ spinel inclusions along with a small amount of CaO–MgO–Al₂O₃ were the main inclusions in Fe–Al alloys. MgO·Al₂O₃ inclusions were mainly formed at the interface by alloy/refractory interactions and then mechanically transferred into molten alloys.