A5066558321- High-pressure geophysics and materials
- Energetic Materials and Combustion
- High-Velocity Impact and Material Behavior
- Boron and Carbon Nanomaterials Research
- Ion-surface interactions and analysis
- Rare-earth and actinide compounds
- Intermetallics and Advanced Alloy Properties
- Diamond and Carbon-based Materials Research
- Laser-induced spectroscopy and plasma
- Nuclear Materials and Properties
- Magnesium Alloys: Properties and Applications
- Thermodynamic and Structural Properties of Metals and Alloys
- Powder Metallurgy Techniques and Materials
- X-ray Diffraction in Crystallography
- Thermal and Kinetic Analysis
- Structural Response to Dynamic Loads
- Electron and X-Ray Spectroscopy Techniques
- Microstructure and mechanical properties
- Nuclear materials and radiation effects
- Additive Manufacturing and 3D Printing Technologies
- Advanced ceramic materials synthesis
- Advanced machining processes and optimization
- Crystallography and molecular interactions
- Magnesium Oxide Properties and Applications
- Advanced X-ray Imaging Techniques
Los Alamos National Laboratory
2020-2023
Purdue University West Lafayette
2016-2022
Eglin Air Force Base
2020
Georgia Institute of Technology
2020
University of Notre Dame
2017
Time-resolved x-ray diffraction was used to examine the phase evolution of polycrystalline Mg shocked along principal Hugoniot states that span multiple boundaries into liquid. The data indicate hcp-bcc boundary lies above 27 GPa, with transition occurring within nanoseconds loading. Experiments at 55 GPa reveal a mixture bcc and liquid, indicating incipient melt 10--15 lower than previously reported, complete melting observed 63 GPa.
Knowing the relationship between three-dimensional structure and properties is paramount for complete understanding of material behavior. In this work, internal nanostructure micrometer-size (∼10 µm) composite Ni/Al particles was analyzed using two different approaches. The first technique, synchrotron-based X-ray nanotomography, a nondestructive method that can attain resolutions tens nanometers. second destructive technique with sub-nanometer resolution utilizing scanning electron...
The performance of energetic materials subjected to dynamic loading significantly depends on their micro- and meso-scale structural morphology. geometric versatility offered by additive manufacturing opens new pathways tailor the these materials. Additively manufactured (AMEMs) have a wide range characteristics with hierarchy length scales process-inherent heterogeneities, which are hitherto difficult precisely control. It is important understand how features affect AMEMs’ response under...
The high-temperature and high-pressure response of magnesium has been investigated through shock-release experiments performed up to shock melting. longitudinal bulk sound speeds Mg are reported along the Hugoniot from 25 56 GPa used determine elastic properties Gr\"uneisen parameter. hexagonal close-packed (hcp)--body-centered cubic (bcc) phase transition is marked by a reduction in determined shear wave speed. Thermal softening observed begin between 40 44 GPa, with incipient melt at 55.5...
Here, we report ultra-fast (0.1–5 μs) shock-induced reactions in the 3B-TiN system, leading to direct synthesis of cubic boron nitride, which is extremely rare nature and second hardest material known. Composite powders were produced through high-energy ball milling provide intimate mixing subsequently shocked using an explosive charge. High-resolution transmission electron microscopy X-ray diffraction confirm formation nanocrystalline grains c-BN during metathetical reaction between...
Nanothermite NiO–Al is a promising material system for low gas emission heat sources; yet, its reactive properties are highly dependent on processing conditions. In the current study, sputter deposition used to fabricate controlled nanolaminates comprised of alternating NiO and Al layers. Films having an overall stoichiometry 2Al 3NiO were produced with different bilayer thicknesses investigate how ignition self-sustained, high temperature reactions vary changes nanometer-scale periodicity...
Time-resolved x-ray diffraction (XRD) was used to examine the behavior of Ce under shock loading stress states up 22 GPa that span shock-melt transition. Experiments reported here observed held at a steady state for ∼500 ns prior being uniaxially released ambient pressure. XRD shows constant pattern over duration with rapid solidification occurring on release. Cerium found remain crystalline as Poisson's ratio (ν) increases in α-phase incipient melt once ν reaches 0.5. Diffraction results...
Recent examination of the cerium Hugoniot with pyrometry and x-ray diffraction (XRD) has revealed a narrow solid-liquid two-phase region. It been suggested that nonequilibrium melting may be occurring along Ce Hugoniot, either melt kinetics or sluggish \ensuremath{\alpha}-\ensuremath{\epsilon} transition impeding transition. In particular, is unknown location phase boundary in dispute. Static measurements suggest nearly vertical intersects at 6--7 GPa. This lies direct conflict dynamic...
The formation of liquid following release from a shocked state governs the transition spall to cavitation and ejecta in metals. In order build physics-based models these processes, it is necessary critically evaluate relative importance kinetics entropy generation during along with accuracy multiphase equations state. Tin (Sn) has served as testbed for variety experiments examining strength due its accessible melt boundary solid–solid phase transitions. This work presents evolution high...
Understanding the mechanisms of shock-induced reaction is important for gaining potential control over synthesis novel materials with enhanced properties. Toward this, shock responses a physical mixture Ni/Al powders and composite powder produced through high-energy ball milling (HEBM) were examined compared. Powder samples pressed to ∼73% TMD compressed peak stresses between ∼10 – 20 GPa resulting wave profiles measured using laser velocimetry (PDV). Longitudinal stress (Px) particle...
We report a method to measure the temperature and transition time of cerium resolidification after shock liquid phase. Coating highly reactive metal onto an inert optical window allows supported take pure sample through isobaric thermodynamic trajectory as diffusion cools under steady stress. liquid-to-epsilon transformation at range pressures map melt boundary dynamic compression. use duration bound kinetics, constrain enthalpy entropy, explain discrepancies in predicted Hugoniot...