Abstract
Ultrafine Cu-3vol.%CuO.Al₂O₃ powder system with the mean copper crystallite size of 28 nm was prepared by combination of mechanical milling with phase transformations of the powder system. The final preparation operation was a strongly exothermic reaction of chemical reduction of CuO-CuO.Al₂O₃ mixture to Cu-3vol.%CuO.Al₂O₃, during which the clustering of fine-sized Cu particles and of secondary phase nanoparticles can take place. By 8 hours intensive milling of the mixture prepared in such a way, the mean size of the copper crystallites decreased to 11 nm. The work analyses the influence of the preparation conditions on the morphology and the microstructural parameters of the Cu-matrix in each stage of preparation with the emphasis on the formation of such characteristics of the resulting powder that will ensure the thermal stability of the interfaces and will be advantageous from the viewpoint of subsequent compacting of the powder mixture.

Key words
ultrafine powders, copper, mechanical milling, morphology, microstructure, thermal stability

Full text not available