Manipulating shock waves with metallurgy

Existing methods for disrupting shock waves employ low-density materials and mesostructures, which occupy significant space, are difficult to fabricate, and are often destroyed after loading. In this work we produce a gradient metamaterial with near-uniform density capable of disrupting shock waves fifty-fold in time. We utilize metastable volumetric contraction at the atomic-scale during alpha <->epsilon phase transformation in Fe-based alloys to disrupt shock waves. Gradient Fe-xMn alloys are fabricated and shock compressed to pressures approaching 13 GPa, with shock rise times increasing from similar to 20 ns in pure Fe to similar to 10 00 ns in the Fe-xMn laminate. Shock-recovered microstructures indicate that the phases reversibly transform. Two-dimensional simulations, validated against planar experiments, predict geometries that can effectively focus or dissipate shock waves. To our knowledge, this work is the first to demonstrate manipulation of shock waves via alloying of phase-transforming metamaterials. Published by Elsevier Ltd on behalf of Acta Materialia Inc.