  Correlated electrons in a binary alloy $A_{x}B_{1-x}$ are investigated within
the Hubbard model and dynamical mean--field theory (DMFT). The random energies
$\epsilon_{i}$ have a bimodal probability distribution and an energy separation
$\Delta $. We solve the DMFT equations by the numerical renormalization group
method at zero temperature, and calculate the spectral density as a function of
disorder strength $\Delta $ and interaction $U$ at different fillings. For
filling factors $\nu =x$ or $1+x$ the lower or upper alloy subband is half
filled and the system becomes a Mott insulator at strong interactions, with a
correlation gap at the Fermi level. At the metal--insulator transition
hysteresis is observed. We also analyze the effective theory in the $\Delta \to
\infty $ limit and find good agreement between analytical and numerical results
for the critical interaction $U_{c}$ at which the metal--insulator transition
occurs.
