A5036619351- Rare-earth and actinide compounds
- Nuclear Materials and Properties
- High-pressure geophysics and materials
- Magnetic Properties of Alloys
- Microstructure and mechanical properties
- Diamond and Carbon-based Materials Research
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Intermetallics and Advanced Alloy Properties
- Thermodynamic and Structural Properties of Metals and Alloys
- Fusion materials and technologies
- Nuclear physics research studies
- Metal and Thin Film Mechanics
- Metallurgical and Alloy Processes
- Ion-surface interactions and analysis
- Advanced ceramic materials synthesis
- Radioactive element chemistry and processing
- Additive Manufacturing and 3D Printing Technologies
- Advanced materials and composites
- Hydrogen embrittlement and corrosion behaviors in metals
- Energetic Materials and Combustion
- High-Velocity Impact and Material Behavior
- Advanced Materials Characterization Techniques
- Aluminum Alloys Composites Properties
Lawrence Livermore National Laboratory
2010-2022
Sandia National Laboratories
2011
United States Department of Commerce
2010-2011
Smithsonian Institution
2010
University of California, Los Angeles
2010
University of Washington
2010
Johns Hopkins University
2003
Self-propagating formation reactions have been studied in multilayer foils and they are currently being investigated for applications joining ignition. Here, we introduce a reactive foil which contains reduction-oxidation thermite reaction between CuOx Al. Typically foils, elemental layers react form single intermetallic product. In this reaction, however, aluminum copper oxide are, respectively, oxidized reduced copper. The fully dense provide well-defined geometry studying the...
A basic tenet of material science is that the flow stress a metal increases as its grain size decreases, an effect described by Hall-Petch relation. This relation used extensively in design to optimize hardness, durability, survivability, and ductility structural metals. Letter reports experimental results new regime high pressures strain rates challenge this mechanical metallurgy. We report measurements plastic model body-centered-cubic tantalum made under conditions pressure (>100 GPa)...
We report details of an experimental platform implemented at the National Ignition Facility to obtain in situ powder diffraction data from solids dynamically compressed extreme pressures. Thin samples are sandwiched between tamper layers and ramp using a gradual increase drive-laser irradiance. Pressure history sample is determined high-precision velocimetry measurements. Up two independently timed pulses x rays produced or near time peak pressure by laser illumination thin metal foils. The...
CuO x / Al exothermic reactions in multilayer foils were studied to identify reaction paths and kinetics. Heating samples at a slow, controlled rate differential thermal analyzer showed that the reduction of CuOx oxidation proceeded via two separate exotherms. To analyze this pathway, heated various temperatures within these exotherms, quenched, characterized with x-ray diffraction, Auger depth profiling, transmission electron microscopy. Experimental evidence indicates first reaction, is...
We are studying material strength at high pressures (>1 Mbar) and strain rates (106 - 108 sec-1) in Ta using the Omega laser. The sample is maintained well below melt temperature a quasi-isentropic ramped drive based on reservoir-gap-sample configuration. inferred from measurements of growth pre-imposed sinusoidal ripples via Rayleigh-Taylor (RT) instability. can greatly suppress RT rate an effective lattice viscosity (H. S. Park, et al., Phys. Rev. Lett. 104, 135504 (2010)). Our recent...
The concept of a gradient piston drive has been extended from that single component reservoir, such as high explosive, to multi-component reservoir utilizes low density foams and large shocks achieve pressures (∼3.5 mbar) controlled pressure vs. time profiles on driven sample. Simulated experimental drives shaped through the use multiple (including carbonized resorcinol formaldehyde SiO2 foam) reservoirs are compared. Individual layers in shown correlate with velocity features measured which...
The solid-solid phase transition between the bcc (α) and hcp (ε) lattice structures in iron is known to occur as material compressed. When kept below its melting point, an effective increase macroscopic strength of accompanies this transition. Understanding throughout deformation process presents a significant computational challenge, but important for improving models planetary structure, including interpretation seismic measurements taken through our own Earth's core.To explore at high...
Extended x-ray absorption fine structure spectroscopy (EXAFS) is used to investigate the local atomic environment and vibrational properties of plutonium gallium atoms in ${\ensuremath{\alpha}}^{\ensuremath{'}}$ \ensuremath{\delta} phases a mixed phase Pu-Ga alloy. EXAFS results measured at low temperature compare sample with single-phase \ensuremath{\delta}-Pu sample. spectral components attributed both ${\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{-}\mathrm{Pu}$ were observed Ga...
The local atomic environment and vibrational properties of atoms in monoclinic pure $\ensuremath{\alpha}$-plutonium as well orthorhombic $\ensuremath{\alpha}$-uranium its low-temperature charge-density-wave (CDW) modulation are examined by extended x-ray absorption fine structure spectroscopy (EXAFS). Pu ${L}_{\mathrm{III}}$-edge U EXAFS data measured at low temperatures verify the crystal structures $\ensuremath{\alpha}$-U $\ensuremath{\alpha}$-Pu samples previously determined diffraction...
By alloying Pu with Ga, the face-centered-cubic $\ensuremath{\delta}$ phase can be retained down to room temperature in a metstable configuration, which ultimately yields chemical driving forces by undergoing $\ensuremath{\delta}\ensuremath{\rightarrow}{\ensuremath{\alpha}}^{\ensuremath{'}}$ isothermal martensitic transformation below ${M}_{s}\ensuremath{\approx}\ensuremath{-}100\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$. This is found exhibit anomalous kinetics, nature of has...
Resonant photoemission, a variant of photoelectron spectroscopy, has been demonstrated to have sensitivity aging Pu samples. The spectroscopic results are correlated with resistivity measurements and shown be the fingerprint mesoscopic or nanoscale internal damage in physical structure. This means that signature due established.
Blistering and delamination are the primary failure mechanisms during processing of depleted uranium (DU) hohlraums. These hohlraums consist a sputter-deposited DU layer sandwiched between two layers gold; final thick gold is electrodeposited on exterior. The hohlraum deposited copper-coated aluminum mandrel; Al Cu removed with chemical etching after deposited. After mandrel removed, blistering observed interiors some hohlraums, particularly at radius region. It hypothesized that blisters...
Enthalpy and entropy are thermodynamic quantities critical to determining how at what temperature a phase transition occurs. At transition, the enthalpy temperature-weighted differences between two phases equal ($\ensuremath{\Delta}H=T\ensuremath{\Delta}S$), but there materials where this balance has not been experimentally or theoretically realized, leading idea of hidden order disorder. In Pu-1.9 at. $%$ Ga alloy, $\ensuremath{\delta}$ is retained as metastable state room temperature, low...
Depleted uranium (DU) hohlraums consist of a sputter-deposited DU layer sandwiched between two layers gold and overcoated with thick electrodeposited layer. Production multilayered system dissimilar materials to tight tolerances requires complex set process steps. Process drift in production resulted increased failures led unacceptably low yields. Characterization this failure mechanism indicated poor adhesion layers. Failure one could be traced the preceding Ultimately, were pretreatment...