Effect of extrusion on microstructure and properties of a submicron crystalline Cu-5 wt.%Cr alloy

The submicron crystalline Cu-5 wt.%Cr alloy, prepared by mechanical alloying and hot press sintering, was extruded at various temperatures from 100 degrees C to 900 degrees C, and the effects of extrusion ratio and temperature on microstructure and properties have been investigated. The results show that, by extrusion, the Cu grains of alloy can be further refined, and the higher the extrusion ratio, the finer and more homogeneous the as-extruded microstructure. Though the Cr particles in the alloy can be hardly deformed or refined during extrusion, they can prevent the dynamically recrystallized Cu grains from overgrowth. The extrusion temperature has significant effect on the microstructure feature of the Cu matrix. Different extrusion temperatures lead to different deformation types and corresponding microstructure features. The optimal extrusion temperature of the alloy is 600 degrees C. By extrusion at 600 degrees C, the finest dynamically recrystallized grains of about 200 nm can be obtained, and the alloy presents both high strength and good ductility. (C) 2008 Elsevier B.V. All rights reserved.