Small Scale Oxidation Experiments on AlMg Alloys in Various Gas Fired Furnace Atmospheres

Oxidation is of great interest in the casthouse, as oxidation equates to metal loss. Therefore, a method to study the oxidation in a casthouse was developed and tested on AlMg alloys and AlMg alloys with beryllium additions under a variety of atmospheres created by an airfuel or oxyfuel burners. Samples of around 65 grams with between 0 and 5% Mg were placed in small steel or ceramic crucibles and further placed in a gas-fired box furnace for times between 10 min and 6 h. The sample mass was recorded after cooling to quantify the oxidation extent with respect to both alloy and atmosphere. Microscopic analysis of selected samples showed that a MgAl₂O₄ layer had formed on the surface and that at higher Mg contents internal oxidation occurred resulting in the formation of MgO or MgAl₂O₄ clusters in the melt. The results show promise for a method to give an increased understanding of the oxidation in the casthouse.