14 research outputs found
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Elastic and plastic properties of uranium dioxide from 5 to 330 GPa
Published Hugoniot data for UO/sub 2/ is in error, because the measuring techniques used did not resolve the strong multiple-wave shock-structures present. Hence calculations related to liquid metal, fast-breeder-reactor, excursion analyses based on extrapolations of that data are in serious error. The inclined prism, flash gap, and two-stage gas-gun techniques are used to determine shock-compression parameters for UO/sub 2/ to 300 GPa. The Hugoniot elastic limit for UO/sub 2/ was found to be 5.7 GPa. At higher pressure, a plot of shock vs particle velocity displays a discontinuity between 1.0 < U/sub p/ < 1.8 km/s, which appears to be a manifestation of a solid-solid phase transition. For 1.8 < U/sub p/ < 4.0 km/s, the plot is given by U/sub s/ = 5.8 + 1.28 (U/sub p/ - 1.8)
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Hugoniot elastic limits and compression parameters for brittle materials
The physical properties of brittle materials are of interest because of the rapidly expanding use of these material in high-pressure and shock wave techology, e.g., geophysics and explosive compaction as well as military applications. These materials are characterized by unusually high sonic velocities, have large dynamic impedances and exhibit large dynamic yield strengths
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Elastic and plastic properties of uranium dioxide from 5 to 330 GPa
We have measured the shock-compression parameters for UO/sub 2/ to 330 GPa. The Hugoniot elastic limit was found to be 5.7 GPa. Evidence for a shock-induced phase transition was observed at about 54 GPa
Australia Antigen (HB-Ag) Subtyping by a Sensitive Tanned Cell Haemagglutination-Inhibition Technique
The influence of the shock compression conditions on the graphite transformations into lonsdaleite and diamond
Shock compression of [001] single crystal silicon
Silicon is ubiquitous in our advanced technological society, yet our current understanding of change to its mechanical response at extreme pressures and strain-rates is far from complete. This is due to its brittleness, making recovery experiments difficult. High-power, short-duration, laser-driven, shock compression and recovery experiments on [001] silicon (using impedance-matched momentum traps) unveiled remarkable structural changes observed by transmission electron microscopy. As laser energy increases, corresponding to an increase in peak shock pressure, the following plastic responses are are observed: surface cleavage along {111} planes, dislocations and stacking faults; bands of amorphized material initially forming on crystallographic orientations consistent with dislocation slip; and coarse regions of amorphized material. Molecular dynamics simulations approach equivalent length and time scales to laser experiments and reveal the evolution of shock-induced partial dislocations and their crucial role in the preliminary stages of amorphization. Application of coupled hydrostatic and shear stresses produce amorphization below the hydrostatically determined critical melting pressure under dynamic shock compression