Abstract
A microscopic-level understanding of the high-pressure states achieved under shock compression, including comparisons with static compression, is a long-standing and important scientific challenge. Unlike hydrostatic compression, uniaxial strains inherent to shock compression result in plastic deformation and abundant lattice defects. At high pressures (), the role of shock-induced deformation and defects remains an open question. Because of the nanosecond time scales in shock experiments, real-time in situ observations of shock-induced lattice defects have been challenging. Here, we present synchrotron x-ray diffraction measurements on laser-shock-compressed gold that provide the first unambiguous in situ measurements of stacking faults (SFs), likely formed by partial dislocations, during shock compression. SF abundance increases monotonically with shock compression up to 150 GPa, where SFs comprise almost every 6th atomic layer. Our results show that SFs play an important role in the plastic deformation of face-centered-cubic metals shocked to high stresses, providing a quantitative benchmark for future theoretical developments.
- Received 23 May 2019
- Revised 15 November 2019
DOI:https://doi.org/10.1103/PhysRevX.10.011010
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
The highest-pressure states of matter achievable in the laboratory are obtained using shock-wave compression (as encountered, for example, in high-velocity impacts and explosions). Unlike hydrostatic compression, shock-wave compression of solids results in plastic deformation and abundant lattice defects. Although quantitative measurements of these defects during shock compression are essential to understanding the shocked states of materials, real-time measurements have posed a significant challenge because of the very short (nanosecond) timescales of the experiments. Here, we report the use of recently developed experimental capabilities to quantitatively observe, in real time, the formation of lattice defects during shock compression.
For face-centered-cubic (fcc) metals, shock-induced deformation is expected to give rise to the formation of stacking faults, defined as alterations of the stacking sequence of atomic layers. Though theoretically expected, real-time measurements of stacking faults under shock compression of these metals have not been reported so far. Coupling in situ synchrotron x-ray diffraction with laser-shock-compression experiments, we have measured the abundance of stacking faults generated in gold, a representative monatomic fcc metal, shock compressed to high stresses reaching 150 GPa. Our results show that stacking-fault abundance increases monotonically with shock compression, so that almost every sixth atomic layer is a stacking fault at 150 GPa.
These results provide new insight into the important role of stacking faults during shock-induced deformation in fcc materials and will serve as a quantitative benchmark for future theoretical developments.