THERMODYNAMICS AND MORPHOLOGY OF THE AMORPHIZATION REACTION DURING THE ROD-MILLING OF AL-50 AT PERCENT-TA ALLOY POWDER

A report is presented on the crystalline to amorphous phase transition induced by the rod-milling of a mixture of Al and Ta powders using the mechanical alloying method. Based on the thermal and morphological analyses, it is shown that the mechanical alloying process is classified into three stages, i.e., the agglomeration, amorphization and homogenization stages. During the agglomeration and amorphization stages, a thermal-assisted amorphization leads to the formation of an amorphous phase by a solid-state amorphization reaction. At the homogenization stage, however, an amorphous phase with fine nanostructure is formed due to the mechanical driving force generated by the shear force of the rods.