Amorphization and nanocrystallization of silcon under shock compression

In collaboration with LLNL and Caltech, experiments to test the strain rate and texture dependence of spall strength in tantalum were conducted at Janus in the Jupiter Laser Facility at LLNL from June-July 2014. Part of the laser shots were dedicated to reproducing data from the last set of spall experiments in 2012 and the rest of the laser shots were dedicated to produce new science on spall strength. Experiments were also conducted at the Omega Facility (LLE, U. of Rochester). The limits of spall strength were tested by increasing the strain rate and changing the texture of the samples. This research was successfully completed and a paper has just appeared in Acta materialia. Four papers on amorphization in Si, Ge, B4C, and SiC were published in leading journals. We have now demonstrated that amorphization is an important mechanism of inelastic deformation in covalently bonded solids under shock compression.