  We investigate the influence of interference between Coulomb interaction and
impurity scattering on the static electronic response $\chi (0,q)$ in
disordered metals to leading order in the effective Coulomb interaction. When
the transport relaxation time $\tau _{tr}$ is much shorter than the
quasiparticle life time, we find a $\mbox{sgn}(2p_F-q)/\sqrt{|2p_F-q|}$
divergence of the polarization function at the Fermi surface ($q=2p_F$). It
causes a phase shift of the Friedel oscillations as well as an enhancement of
their amplitude. Our results are consistent with experiments and may be
relevant for understanding the stability of the amorphous state of certain
alloys against crystallization.
