| Abstract: | Both the coarsening of Al_2O_3 nanoparticles and the growth of Cu nanograins of mechanically milled nanostructured Cu-5 vol.%Al_2O_3 composites with, and without, trace amounts of Ti during annealing at973 K for 1 h were investigated. It was found that doping with a small amount of Ti(e.g. 0.2 wt%) in a nanostructured Cu-5 vol.%Al_2O_3 composite effectively suppressed the coarsening of Al_2O_3 nanoparticles during exposure at this temperature. Further, the Ti addition also prevented the concomitant abnormal growth of the copper grains normally caused by the coarsening of the Al_2O_3 nanoparticles. Energy dispersive X-ray spectroscopy analysis of the Al_2O_3 nanoparticles in the annealed Cu-5 vol.%Al2 O3-0.2 wt%Ti sample suggested that the Ti atoms either diffused into the Al_2O_3 nanoparticles or segregated to the Cu/Al_2O_3 interfaces to form Ti-doped Al_2O_3 nanoparticles, which was more stable than Ti-free Al_2O_3 nanoparticles during annealing at high homologous temperatures. |
