Influence of high-energy ball milling on electrical resistance of Cu and Cu/Cr nanocomposite materials produced by Spark Plasma Sintering

A combination of High Energy Ball Milling in the planetary mills (HEBM) with Spark Plasma Sintering (SPS) allows production of dense (>97%) nano-composites of immiscible metals, Cu and Cr, so-called pseudo-alloys. New results on electrical resistance of the pseudo-alloys have been obtained from cryogenic to elevated temperatures, in comparison with the Cu-Cr micro-composites and pure Cu. The results show that duration of HEBM influences hardness and electric resistivity of the materials in a wide temperature range, including cryogenic residual resistivity. This influence remains after SPS. Increasing of the electrical resistivity and hardness with increasing of the mechanical impact is explained by significant increase of specific surface of grain boundaries due to grains refinement. At the same time, some regimes of HEBM results in increasing of the electrical conductivity (decreasing resistance) due to mechanical boundaries purification. These findings allow optimization of the process for preparation of the alloys with desired electrical conductivity and mechanical properties, specifically for application as electrode materials.