Superplasticicity of Cu-16 at.% Ag microcomposites

Superplastic behavior of heavily drawn Cu-at.% Ag filamentary microcomposite wires was investigated. The filamentary microstructure tended to break up at high temperatures by spheroidization, grooving, and/or recrystallization because of its high interface energy and high cold-work energy. Above 400 degreesC, extensive recrystallization occurred and the grains 300-500 nm in size were observed in the Cu matrix. As the deformation proceeded, the elongated silver lamellae and/or the region with numerous filaments broke up and rearranged into chevron patterns, which mostly lay perpendicular to the loading axis. The elongation up to 1000% was obtained at 500 degreesC at the strain rates of 7 x 10(-4)/s and -3 x 10(-3)/s, and the elongation up to 600% was obtained at 400 degreesC at the strain rate of 1 x 10(-4)/s. Arrays of dislocations in the matrix and near grain and phase boundaries were observed after superplastic deformation, supporting the slip-accommodated grain and/or phase boundary sliding.