X-ray diffraction from shock driven Sn microjets

In situ x-ray diffraction was performed on shock-generated microjets composed of Sn and Sn-4Ag. Under low pressure drives (similar to 21 GPa), a significant fraction of the jet volume was found to be in the beta - Sn phase, and these crystallites were much smaller than the initial grain size of the material. Significant quantities of amorphous (molten) material were observed for higher drive pressures (similar to 25-35 GPa). The extent of melting at these pressures was greater than would be predicted for uniaxial shock loading. Diffraction patterns from the Sn-4Ag alloy showed a peak that is consistent with the expected Ag3Sn intermetallic phase. This peak remained evident under drive conditions where the sample was otherwise fully amorphous. This indicates a slushy or a mixed phase of liquid Sn and solid Ag3Sn. Given the eutectic character of this alloy, this observation is attributed to a kinetic limitation on the dissolution of Ag3Sn. This implies that a much broader range of drive conditions will lead to mixed phase jets and ejecta than would be predicted from the equilibrium melt boundary of such alloys. Published under an exclusive license by AIP Publishing.