Microstructural aspects of rolling deformation in ultrafine-grained copper

Abstract

Ultrafine-grained (UFG) copper produced by severe plastic deformation demonstrates an unusual combination of high strength and rather high ductility at room temperature. To obtain the UFG microstructure, the equal channel angular extrusion technique was used in the current work. The microstructure, crystallographic texture and grain boundary distributions were studied in as received and cold-rolled samples. The microstructures and textures generated by rolling of the UFG sample were compared with those formed in identically rolled conventional coarse-grained copper. Rolling to 83° resulted in drastic changes of all microstructural parameters owing to the transformation of the microstructure with initially equiaxed grains into a banded microstructure with mainly elongated and subdivided grains having orientations typical of a rolling texture. Additional rolling led to the strengthening of the main texture components. The emergence of cube oriented {001}(100) grains was distinguished in the rolled UFG samples. During storage at ambient temperature these grains grew at the expense of deformed adjacent grains, thus transforming the rolled UFG microstructure into a partially recrystallized state.