The oxidation behavior of stir-cast and heat-treated EV31A at high temperatures in an air atmosphere

Abstract

This study examines the influence of heat treatment techniques on the oxidation behavior of stir-cast EV31A magnesium alloy. The oxidation behavior of the alloy was examined under isothermal conditions at three different temperatures: 390 °C, 455 °C, and 520 °C, by evaluating its weight change. Before and after oxidation, FE-SEM with EDS and XRD were used to detect the alloy's shape, composition, and phases. In contrast to heat-treated alloy, the as-cast material oxidizes quickly. The oxidation behavior of EV31A follows linear kinetics. It creates a dense oxide layer with a thickness of 17.97 µm, which may be resistant to further oxidation. At 520 ⁰C, the oxidation behavior of EV31A changed. The oxidation rate of the as-cast alloy is greater than that of the heat-treated alloy. The formation of dual phase of MgO – Nd2O3 on the surface is noticeable. It confirms that the intermetallic phases significantly modify the oxidation behavior.