The present study examines nanocomposites prepared by mechanical alloying of copper with other transition elements, which will produce a dispersion of stable boride and carbides reinforcement particles within a nanostructured copper matrix, at room temperature. Copper, niobium, boron and graphite powder mixtures were mechanically alloyed for several hours in a planetary ball-mill, in argon atmosphere and using a stainless steel container. The powder mixtures were produced with nominal composition of 10-30 vol.% NbC and 7-10 vol.% NbB2, using powders of pure elemental Cu, Nb, synthetic graphite and crystalline boron. The microstructural changes during milling of these powder mixtures were studied using X-ray diffraction, optical microscopy, scanning electron microscopy and microhardness measurements.