  We observed dynamically driven phase transitions in isentropically compressed
bismuth. By changing the stress loading conditions we explored two distinct
cases: one in which the experimental signature of the phase transformation
corresponds to phase-boundary crossings initiated at both sample interfaces,
and another in which the experimental trace is due to a single advancing
transformation front in the bulk of the material. We introduce a coupled
kinetics - hydrodynamics model that for this second case enables us, under
suitable simplifying assumptions, to directly extract characteristic transition
times from the experimental measurements.
