  A Cu-Fe nanocomposite containing 50 nm thick iron filaments dispersed in a
copper matrix was processed by torsion under high pressure at various strain
rates and temperatures. The resulting nanostructures were characterized by
transmission electron microscopy, atom probe tomography and M\"ossbauer
spectrometry. It is shown that alpha-Fe filaments are dissolved during severe
plastic deformation leading to the formation of a homogeneous supersaturated
solid solution of about 12 at.% Fe in fcc Cu. The dissolution rate is
proportional to the total plastic strain but is not very sensitive to the
strain rate. Similar results were found for samples processed at liquid
nitrogen temperature. APT data revealed asymmetric composition gradients
resulting from the deformation induced intermixing. On the basis of these
experimental data, the formation of the supersaturated solid solutions is
discussed
