Diffusion of Cu in AlCu alloys of different composition by quasielastic neutron scattering

Quasielastic cold neutron scattering experiments on molten Al1−xCux alloys (x = 0.10, 0.17 and 0.25) have been performed at three different temperatures on the FOCUS time-of-flight spectrometer at the Swiss neutron spallation source SINQ. As the main part of the scattering at small Q is incoherent and originating from Cu, self-diffusion coefficients D for the Cu ions could be determined from the widths of quasielastic peaks. The derived values are considerably larger than those found in capillary tube measurements. Even if the accuracy in the determination of D is better than about 4% it could not be concluded whether the temperature variation of D follows an Arrhenius law or a power law.