Effect of calcium on the combustion behavior of molten AZ91 magnesium alloy

Abstract

In this study, to obtain guidelines for inhibiting the combustion of the molten metal in magnesium alloys, AZ91D magnesium alloy and AZ91 magnesium alloy with added calcium were exposed to the atmosphere, and the surfaces of the alloys were observed. In the case of AZ91D magnesium alloy, aggregated products were observed on the surface of the molten alloy. In the case of AZ91 alloy with added calcium, aggregated products were not observed. A CaO layer was formed on the outermost surface of the molten alloy, and a MgO layer was formed below the CaO layer. With increasing exposure time, the thicknesses of these layers remained almost constant. It was considered that the CaO layer, in which aluminum did not appear, inhibited combustion by limiting the flow of magnesium vapor from the molten alloy to the atmosphere and the oxidation of magnesium over a long time. 2019 The Japan Institute of Metals and Materials.