THE HIGH-TEMPERATURE DEFORMATION OF MECHANICALLY ALLOYED COPPER-BASED ALLOYS

Copper alloys containing 5 vol.% Cr, Nb or Ta have been prepared from mechanically alloyed powders and the mechanical properties examined from room temperature up to 700-degrees-C. The strength observed at room temperature depends on the refinement achieved during the mechanical all stage and maintained during consolidation by extrusion. The strength falls rapidly with increase in temperature, even at temperatures as low as 300-degrees-C. This loss of strength is not associated with structural coarsening at high temperatures nor with the fine grain size of the materials but is due to thermal activation of dislocations over the particle barriers. The observed behaviour is best explained by a stress-assisted process of overcoming these barriers.