Disrupting shock waves with phase transformations

Shock waves compress materials at a strain rate proportional to the peak pressure raised to some exponent, often ranging from 2-4. Phase transformations can be used to split shock waves into multiple, ramped shocks due to their sluggish kinetics relative to shock loading times and dilatational deformation component. The transformation pressure in metals is controlled by the difference in free energy between phases, which is a function of composition. In this work we demonstrate how composition can be varied to control the transformation pressure and shock behavior of materials with a nominal density similar to iron subjected to shocks ranging from 3-30 GPa in. We then fabricate compositionally graded laminates and use experiments to show that they can be used to disrupt shock waves approximately 100-fold in time. Interpretation of experimental results is aided by finite element computations that utilize equation of state information obtained via diamond anvil cell experiments.