  We study ferromagnetic transition in three-dimensional double-exchange model
containing impurities. The influence of both spin fluctuations and impurity
potential on conduction electrons is described in coherent potential
approximation. In the framework of thermodynamic approach we construct Landau
functional for the system "electrons (in disordered environment) + core spins".
Analyzing the Landau functional we calculate the temperature of ferromagnetic
transition $T_C$ and paramagnetic susceptibility $\chi$. For $T_C$, we thus
extend the result obtained by Furukawa in the framework of the Dynamical Mean
Field Approximation, with which our result coincides in the limit of zero
impurity potential. We find, that the alloy disorder, able to produce a gap in
density of electron states, can substantially decrease $T_C$ with respect to
the case of no impurities. We also study the general relation between the
Coherent Potential Approximation and the Dynamical Mean Field Approximation.
