Nanocrystalline structure and strain in magnesium under extreme dynamic compression

Abstract

The study of materials behavior under extreme conditions is fundamental to science and modern technology. Fast ramp compression is a unique method for exploring materials behavior and phase transformations under extreme conditions. One unexplored feature of this method is the nanoscale structure of the material under dynamic compression. This leaves a gap in understanding the details of phase transformations under fast ramp compression. Here, we made a first step in the exploration by applying the Williamson-Hall (WH) analysis to X-ray diffraction data (XRD) measured in magnesium subjected to fast ramp compression at four pressures. We found that at $P=309GPa$ magnesium in bcc-like phase has an average crystalline size $D=(2.2\pm 0.7)nm$ and microstrain $\epsilon =(-0.011\pm 0.007)$. At $P=409GPa$, magnesium demonstrates $D=(4.5\pm 3)nm$ with $\epsilon =(-0.003\pm 0.007)$. At $P=563GPa$, Fmmm magnesium has crystalline size $D=(2.6\pm 0.5)nm$ with microstrain $\epsilon =(-0.004\pm 0.004)$. At $P=959GPa$, we revealed that sh-magnesium exhibits average size of $D>12nm$ and relatively high value of microstrain $\epsilon =(0.011\pm 0.002)$. In the result, we report the first microstructural evolution insights of magnesium under fast ramp compression.

arXiv comment18 pages, 5 figures, 48 refs, 4 figures in Supplementary Materials