Nanoparticle Formation in Magnesium Based Composite by Mg/Al₂O₃ Interfacial Reaction

Abstract

Magnesium based composite containing 10 vol% Al₂O₃ particle was produced by a mechanical milling (MM) and spark plasma sintering (SPS) process and the nanoparticle formation by Mg/Al₂O₃ interfacial reaction was investigated in detail. The microstructural observation of the MM powder and SPS compact was carried out by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). TEM / EDS analysis and XRD result reveal that the nano Mg₁₇Al₁₂ and MgO phases are formed by Mg/Al₂O₃ interfacial reaction. The solute oxygen by Mg/Al₂O₃ interfacial reaction and magnesium of the matrix may immediately produce MgO, because magnesium barely dissolves oxygen. Therefore, many MgO particles are formed at the Mg/Al₂O₃ interface. On the other hand, magnesium can dissolve aluminum to some extent and the aluminum over the solubility limit may bond to magnesium, resulting in the formation of Mg₁₇Al₁₂.