Influence of Al2O3 nanoparticles on solubility extension of Cr in Cu by mechanical alloying

In this study, the effect of the presence of Al2O3 nanoparticles during mechanical alloying on the extension of Cr solid solubility in Cu was investigated. The lattice parameter, dislocation density and crystallite size were evaluated by the X-ray diffraction technique. Also, the microstructure was characterized by scanning electron microscopy and transmission electron microscopy. The final product was a nanocrystalline and supersaturated Cu–Cr solid solution with a mean crystallite size ranging from 8 to 19 nm depending on the composition. The Gibbs free energy changes in these systems due to the dislocation density and crystallite size variations during milling were calculated. It was found that the presence of Al2O3 nanoparticles was beneficial to the process, and this was particularly related to its significant contribution to the increase of strain part of Gibbs free energy changes.