Microstructural development and mechanical properties of nanostructured copper reinforced with SiC nanoparticles

Nanostructured Cu and Cu-2 vol% SiC nanocomposite were produced by high energy mechanical milling and hot pressing technique. Microstructure development during fabrication process was investigated by X-ray diffraction, scanning electron microscope, scanning transmission electron microscope, and electron backscatter diffraction techniques. The results showed that the microstructure of copper and copper-based nanocomposite composed of a mixture of equiaxed nanograins with bimodal and non-random misorientation distribution. The presence of SiC nanoparticles refined the grain structure of the copper matrix while the fraction of low angle grain boundaries was increased. Evaluation of mechanical properties by compression test showed enhanced yield strength from 505±17 MPa for the nanostructured copper to 630±12 MPa for the reinforced metal with 2 vol% SiC. We correlated the strength of the nanostructured materials to their microstructural features based on the strengthening mechanisms. The contribution of different mechanisms including Orowan strengthening, high angle grain boundaries, and density of dislocations were analyzed. It is shown that the high angle grain boundaries in nanostructured materials play a significant role in the strengthening mechanism. The effect of nanoparticles is presented and discussed.