Direct Observation of Shock-Induced Melt Kinetics in a Porous Solid Using Time-Resolved X-Ray Diffraction*

Time-resolved x-ray diffraction was used to obtain direct (real time) evidence of shock-induced melting and associated kinetics in a porous solid (aluminum (Al) powder). Broadening of the Debye-Scherrer ring corresponding to the (111) peak of Al provided unambiguous evidence of melting. Our data showed that complete bulk melting of the powder could take in excess of 450 ns even when it is shocked to equilibrium pressure-temperature states above the melt boundary. Information on the melt kinetics obtained from our work provide insight into the thermal equilibration time and thermal diffusivity of the material under high-pressure dynamic loading, which are essential to developing well-constrained heat transfer and melting models for Al powder and other porous materials (LA-UR-18-30166).