  The interface between a heavy electron coherent metallic phase and an
incoherent normal metal phase is discussed. The Fermi momentum mismatch between
the two phases causes the carriers to scatter at the interface. The interface
conductance is a monotonous increasing function of conduction electron density,
n_c, and is less than 60% of that of a clean heavy fermion metal at
half-filling ($n_c=1$) and can be measured experimentally. Interface
experiments can be used as probe of the nature of the homogenous heavy-fermion
state and provide important information on the effects of inhomogeneities in
heavy-fermion alloys.
