Microstructure and strength of pure Cu with large grains processed by equal channel angular pressing

Abstract

The pure Cu rods with an initial grain size of 410μm were treated by using equal channel angular pressing (ECAP). The deformed microstructure and mechanical properties of ECAPed Cu samples were investigated. Special attention was paid on the refinement of grain size and local micromechanics of ECAPed Cu samples. The original coarse grains were refined to 320μm after 4 passes. The final grains were composed of dislocation cells with a size of 500nm–3μm after 5–8 passes. The yield strength reached a saturation value of 368MPa after 5 passes. The maps of microhardness distribution illustrated the inhomogeneity of local mechanical properties. The dislocation subdivision was the main deformation mode to refine the grain size, while twin fragmentation was restrained by dislocation slips for the reason of large initial grain size. Furthermore, the strengthening of ECAPed Cu was discussed.