Mechanical alloying of amorphous Al-SiO2 powders

Mechanical alloying (MA) of elemental Al and SiO2 mixtures were performed under argon and air atmospheres. Amorphization has been observed in the MA process under argon atmosphere, while MA under air atmosphere the starting materials are still present. The transformation from crystalline to amorphous state was examined using powder X-ray diffraction, transmission electron microscopy and differential thermal analysis. It is believed that the amorphization is due to the destablization of crystalline phase, induced by refinement of grain size, vitrification of pressure, and loss of long range of order in supersaturated solid solution due to interdiffusion.