Microstructures and properties of cold drawn submicron crystalline Cu-5wt%Cr material

By mechanical alloying, hot compacting and hot extrusion, fully densified submicron crystalline Cu-5wt% Cr alloy with high strength and high electrical conductivity has been prepared. Variations of microstructures and properties due to cold drawing of submicron crystalline Cu-5wt%Cr have been investigated. The results show that, by cold drawing, the dislocation density increases and cellular structures are formed. The grainsize of Cu-5wt%Cr alloy is refined from 400~500nm to 100~200nm. When the cold drawn Cu-5wt%Cr is annealed at 550°C, grain size of 200~300nm can be obtained. It demonstrates that the grains of submicron crystalline Cu-5wt%Cr can be further refined through heavy plastic deformation and proper recrystallization. After cold drawing, work -hardening occurs in submicron crystalline Cu-5wt%Cr. With drawing deformation increasing, both the tensile strength and the tensile elongation increase, but the electrical conductivity decreases. The room temperature tensile fracture is caused by the accumulation of pores. These demonstrate that dislocation glide is still the main mechanism in plastic deformation of submicron crystalline Cu-5wt%Cr. With the grains further refining, the ductility of the Cu-5wt%Cr is further improved.