Effect of nano ZrO2 on strengthening and electrical properties of Cu-matrix nanocomposits prepared by mechanical alloying

To improve the mechanical properties of sintered Cu-matrix composites, nano ZrO2 was added up to 12 wt-% and the mechanical alloying technique was used for preparation. After milling, the nanocomposite powders were investigated by X-ray diffraction and transmission electron microscopy. The prepared nanocomposite powders were cold pressed and sintered for 1 h at 750 and 850 degrees C. Furthermore, the microstructure of the sintered specimens was examined by scanning electron microscopy. Moreover, physical, mechanical and electrical properties of sintered specimens were investigated. TEM investigation of the milled powders exhibited homogeneous morphology and particle sizes. Also, it indicated that as the ZrO2 content increases, more uniform distribution of nano-sized ZrO2 particles in the Cu-matrix was achieved and a decrease in the particle size could be obtained. The crystallite size and particle size were decreased and reached to 10.76 and 32.22 nm, respectively, for Cu-12 wt-%wt% ZrO2 nanocomposite. The results revealed also that the microhardness, compressive strength and yield strength of the nanocomposites were increased with increasing of ZrO2 content except fracture strain that reduced significantly. Moreover, all mechanical properties were enhanced much more with the increase of sintering temperature. The electrical conductivity was decreased with the increase of ZrO2 content while it increased with the increase of sintering temperature.