Measuring the melting curve of iron at super-Earth core conditions
High-energy lasers at the National Ignition Facility and in situ x-ray diffraction are used to determine the melting point of iron and the length of dynamo action during core solidification to the hexagonal close-packed structure, finding that terrestrial exoplanets with four to six times Earth's mass have the longest dynamos.
X-ray diffraction at the National Ignition Facility.
- J. R. RyggR. Smith J. Eggert
- 1 April 2020
Physics
This experimental platform has been used up to 2 TPa (20 Mbar) to determine the crystal structure, measure the density, and evaluate the strain-induced texturing of a variety of compressed samples spanning periods 2-7 on the periodic table.
Grain-size-independent plastic flow at ultrahigh pressures and strain rates.
Measurements of the plastic flow of the model body-centered-cubic metal tantalum made under conditions of high pressure and strain rate and the effect of grain size is found to be negligible for grain sizes >0.25 μm sizes.
Extreme Hardening of Pb at High Pressure and Strain Rate.
- A. KrygierP. Powell S. Rothman
- 11 November 2019
Materials Science, Physics
The combination of high-rate, pressure-induced hardening and polymorphism yield an average inferred flow stress of ∼3.8 GPa at high pressure, a ∼250-fold increase, changing Pb from soft to extremely strong.
Directional amorphization of boron carbide subjected to laser shock compression
- Shiteng ZhaoB. Kad M. Meyers
- 12 October 2016
Materials Science, Physics
It is proposed that the shear stresses cause the amorphization and that pressure assists the process by ensuring the integrity of the specimen, and thermal energy conversion calculations including heat transfer suggest that amorphized is a solid-state process.
Directional amorphization of covalently-bonded solids: A generalized deformation mechanism in extreme loading
- Shiteng ZhaoB. Li M. Meyers
- 27 May 2021
Materials Science, Physics
Abstract Shock compression subjects materials to a unique regime of high quasi-hydrostatic pressure and coupled shear stresses for durations on the order of 1–10 nanoseconds for laser-driven loading…
Body-Centered-Cubic Phase Transformation in Gold at TPa Pressures.
- A. ColemanSaransh Singh Raymond F. Smith
- 31 October 2025
Physics, Materials Science
In situ x-ray diffraction at both the National Ignition Facility and Omega-EP Laser Facility has been utilized to determine the crystallographic state of ramp and shock-ramp compressed gold up to 1.2…
Amorphization and nanocrystallization of silicon under shock compression
- Shiteng ZhaoE. Hahn M. Meyers
- 15 January 2016
Materials Science, Physics
Abstract High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon unveiled remarkable structural changes above a pressure threshold. Two distinct…
Pressure and shear-induced amorphization of silicon
- Shiteng ZhaoB. Kad M. Meyers
- 1 December 2015
Physics, Materials Science
Here we report that high-power, pulsed, laser-driven shock compression of monocrystalline silicon produces directional amorphization, revealed by high-resolution transmission electron microscopy and…
Metastability of diamond ramp-compressed to 2 terapascals
- A. LazickiD. McGonegle J. Wark
- 1 January 2021
Physics, Materials Science
The results confirm predictions that the strength of the tetrahedral molecular orbital bonds in diamond persists under enormous pressure, resulting in large energy barriers that hinder conversion to more-stable high-pressure allotropes just as graphite formation from metastable diamond is kinetically hindered at atmospheric pressure.
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