A Cu-6at%Ag cast alloy was deformed by means of high-pressure torsion to different applied strain levels until a steady-state regime is reached. The continuous structural refinement is attended by the successive dissolution of the Ag precipitates in the Cu matrix. The results show that the Ag regions need to fall below a phase size of ~ 5 nm to fully dissolve. Atomistic calculations indicate that the final dissolution can be explained based on the enthalpy difference between the solid solution and layered systems which are in between the coherent and semi-coherent structure. These findings are supported by detailed microstructural investigations.