Nanostructure Cu–Cr alloy with high dissolved Cr contents obtained by mechanical alloying process

Abstract

A nanostructural solid solution of Cu–Cr was prepared by the mechanical alloying process. Three mixtures of Cu powders with 1, 3 and 6 wt-%Cr powders were milled under 250 rev min⁻¹ for different milling times of 4, 12, 48 and 96 h. The mixtures were subsequently compacted and sintered at 450, 600 and 750°C for half an hour. Milled powder mixtures were examined by X-ray diffraction technique, which showed the presence of nanoscale crystallites in the samples and the decrease of lattice parameter of Cu crystals. Sintered powders were investigated by optical microscope and their hardnesses were measured by microhardness. Results showed increasing trends in hardness of the compacted powder mixtures with increasing milling time. Sintering temperature had also evident effects on the behaviour of powder mixtures. As sintering temperature increased, microhardness increased and a peak appeared then a decreasing trend was observed.