  Electrical resistivity evolution during precipitation in Al-Sc alloys is
modeled using cluster dynamics. This mesoscopic modeling has already been shown
to correctly predict the time evolution of the precipitate size distribution.
In this work, we show that it leads too to resistivity predictions in
quantitative agreement with experimental data. We only assume that all clusters
contribute to the resistivity and that each cluster contribution is
proportional to its area. One interesting result is that the resistivity excess
observed during coarsening mainly arises from large clusters and not really
from the solid solution. As a consequence, one cannot assume that resistivity
asymptotic behavior obeys a simple power law as predicted by LSW theory for the
solid solution supersaturation. This forbids any derivation of the precipitate
interface free energy or of the solute diffusion coefficient from resistivity
experimental data in a phase-separating system like Al-Sc supersaturated
alloys.
