Nanocrystalline structure and strain in magnesium under extreme dynamic compression

TL;DR

This paper investigates the nanoscale structure and strain in magnesium subjected to extreme dynamic compression using X-ray diffraction, revealing microstructural evolution at pressures up to 959 GPa.

Contribution

First application of Williamson-Hall analysis to study microstructure of magnesium under fast ramp compression at multiple pressures.

Findings

Crystalline size varies from 2.2 nm to over 12 nm with increasing pressure.

Microstrain in magnesium changes from negative to positive at high pressure.

Provides new microstructural insights into magnesium under extreme 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 $P = 309 GPa$ magnesium in bcc-like phase has an average crystalline size $D = (2.2 \pm 0.7) nm$ and microstrain $\varepsilon = (-0.011 \pm 0.007)$. At $P = 409 GPa$, magnesium demonstrates $D = (4.5 \pm 3) nm$ with $\varepsilon = (-0.003 \pm 0.007)$. At $P = 563 GPa$, Fmmm magnesium has crystalline size $D = (2.6 \pm 0.5) nm$ with microstrain $\varepsilon = (-0.004 \pm 0.004)$. At $P = 959 GPa$, we revealed that sh-magnesium exhibits average size of $D > 12 nm$ and relatively high value of microstrain $\varepsilon = (0.011 \pm 0.002)$. In the result, we report the first microstructural evolution insights of magnesium under fast ramp compression.