  From a simple bulk model for the one-dimensional steady-state solidification
of a dilute binary alloy we derive an interface description, allowing arbitrary
values of the growth velocity. Our derivation leads to exact expressions for
the fluxes and forces at the interface and for the set of Onsager coefficients.
We, moreover, discover a continuous symmetry, which appears in the low-velocity
regime, and there deletes the Onsager sign and symmetry properties. An example
is the generation of the sometimes negative friction coefficient in the
crystallization flux-force relation.
