Stacking-fault energies of solid solution Cu-Ge alloys were obtained by means of X-ray diffraction method and electron microscopy, and also the segregation of solute atoms into stacking faults (Suzuki effect) was examined experimentally. The stacking-fault energy of a Cu-9.13% Ge alloy was given to be 0.88 erg/cm^2 by X-ray method, and 10 erg/cm^2 by electron microscopy. This discrepancy was discussed
