Effect of degassing treatment on mechanical properties of SiC_p/2024Al composites fabricated by powder extrusion

Abstract

The effects of degassing treatment on mechanical properties of the SiC_p/2024Al alloy composites fabricated by powder extrusion were investigated. The degassing temperatures determined from gas chromatography analysis of extracted gases were room temperature and 450°C. The undegassed powders and the powders degassed at room temperature and 450°C were extruded at 500°C. The principal gases extracted by degassing were H₂O and H₂. The thickness and kind of the oxides formed on aluminum powder surface were characterized by Auger electron spectroscopy and scanning electron microscopy. The oxidation of aluminum powder surface was accelerated by H₂O above degassing temperature of 350°C. It was found that the oxides consist of MgO and Al₂O₃. The mechanical properties of the composites degassed at 450°C were higher than those of the undegassed composites and the composites degassed at room temperature. These results show that the degassing treatment at high degassing temperature (~450°C) is necessary to improve the mechanical properties of the SiC_p/2024Al alloy composites by powder extrusion.