Ultrafast dynamic compression technique to study the kinetics of phase transformations in bismuth

Preheated Bi (296-532 K) was ramp compressed with 15-35 ns rise times to a peak stress of similar to 11 GPa to explore structural phase-transformation kinetics under dynamic loading conditions. At high strain rates, epsilon > 5 X 10(6) s(-1), deviation from equilibrium phase boundaries suggests that compression time scales are comparable to the new phase incubation period. The dependence of Delta P/kT on epsilon is consistent with a thermally activated transformation.