Ultrafast X-ray Diffraction Study of a Shock-Compressed Iron Meteorite above 100 GPa

Natural kamacite samples (Fe92.5Ni7.5) from a fragment of the Gibeon meteorite were studied as proxy material for terrestrial cores to examine phase transition kinetics under shock compression range different pressures up 140 GPa. In situ time-resolved X-ray diffraction (XRD) data collected body-centered cubic (bcc) section that transforms high-pressure hexagonal close-packed (hcp) with sub-nanosecond temporal resolution. The coarse-grained crystal rapidly transformed highly oriented crystallites hcp at maximum compression. persisted long 9.5 ns following release. Comparing c/a ratio previous static and dynamic work on Fe Fe-rich Fe-Ni alloys, it was found some shots exhibit larger than ideal ratio, nearly 1.65. This represents first laser structural study natural iron meteorite, relevant understanding properties metallic planetary bodies during impact events Earth’s core elasticity.