Structures and Properties of Mechanically Alloyed Aluminum-Transition Metal Oxide (V2O5, Nb2O5, Ta2O5) Powders and their P/M Materials

In-situ particulate composites can be manufactured from aluminum-oxide system by mechanical alloying followed by the hot consolidation and heat treatment. Powders of transition metal oxides of standard free energies of formation lower than that of SiO2; V2O5, Nb2O5 and Ta2O5 were mechanically alloyed with pure aluminum powder by a high energy ball mill under an argon atmosphere. P/M materials were fabricated from mechanically alloyed powders by cold pressing, vacuum degassing and hot extrusion. Two kinds of process control agent, methanol and graphite were used for mechanical alloying. The solid state reaction of aluminum-oxide systems was studied by X-ray diffraction. In case of graphite as process control agent, formation of Al4C3 and thermite reaction occur faster than in case of methanol. It is shown by X-ray diffraction that P/M materials consist essentially of aluminum-transition metal alloy matrix with dispersion of Al2O3 after heating at 873 K for 10 h. Upon heating of P/M materials at 873 K, the hardness increased due to resulted formation of transition metal aluminides.