Beryllium Reduction Potential in AlMg Cast Alloys

Abstract

Beryllium is used in many aluminium-magnesium alloys to minimize molten metal oxidation and oxide entrainment. As beryllium containing dust and fumes have detrimental effects on health, its use has to be limited. The reduction potential of beryllium has been investigated for AlMg3, AlMg5 and AlMg10 cast alloys as well as Al99.85 as a reference material by thermogravimetric analysis (TGA). The samples were alloyed with Be contents between 3–57 ppm to measure the oxidation inhibiting effect over time. During TGA, the weight gain by oxidation of each sample was measured continuously for 21 h at 750 °C in laboratory scale. The results show that the Be inhibiting effect is lost after a period of time. The samples were analysed by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and electron microscopy (SEM) to further understand the oxidation mechanism. Finally, the results were used to derive a predictive model for the required Be content to protect an AlMg alloy.