A5008569973- Aluminum Alloy Microstructure Properties
- Solidification and crystal growth phenomena
- Metallic Glasses and Amorphous Alloys
- Metallurgical Processes and Thermodynamics
- Nuclear Materials and Properties
- Material Dynamics and Properties
- Glass properties and applications
- Nuclear reactor physics and engineering
- High Temperature Alloys and Creep
- Space Technology and Applications
- Microstructure and mechanical properties
- Metallurgy and Material Forming
- Nuclear and radioactivity studies
- Particle Detector Development and Performance
- nanoparticles nucleation surface interactions
- Additive Manufacturing Materials and Processes
- Fusion materials and technologies
- Microstructure and Mechanical Properties of Steels
- Nuclear Physics and Applications
- Thermodynamic and Structural Properties of Metals and Alloys
- Intermetallics and Advanced Alloy Properties
- Metallurgical and Alloy Processes
- Electron and X-Ray Spectroscopy Techniques
- Advanced materials and composites
- Phase-change materials and chalcogenides
Los Alamos National Laboratory
2015-2024
IMDEA Materials
2020
SLAC National Accelerator Laboratory
2020
Colorado School of Mines
2020
Argonne National Laboratory
2020
University of Wisconsin–Madison
2009-2012
Significance A shear band is a region of highly localized plastic flow that develops during loading in both crystalline and amorphous materials. Shear bands directly determine the ductility an phase, but relatively little known about their nucleation. We use nanoindentation to probe nucleation by measuring first pop-in event which associated with formation. analyze large number independent measurements on four different metallic glasses reveal bimodal distribution events operate at stress...
X-ray imaging, which permits the microscopic visualization of metal alloy solidification dynamics, can be coupled with controlled to create microstructures by design. This x-ray image shows a process-derived composite microstructure being made from eutectic Al-17.1 at.%Cu successive and remelting steps. Controlling structure or is challenging, but has significant technological implications for casting crystal growth. Here, we couple synchrotron imaging visualize growth stray crystals in...
The high density of aluminum nanocrystals (>1021 m-3) that develop during the primary crystallization in Al-based metallic glasses indicates a nucleation rate (∼1018 m-3 s-1). Several studies have been advanced to account for behavior, but none developed completely describe reaction kinetics. Recently, structural analysis by fluctuation electron microscopy has demonstrated presence Al-like medium range order (MRO) regions as spatial heterogeneity as-spun Al88Y7Fe5 glass is representative...
We present a three-dimensional (3D) extension of previously proposed multi-scale Dendritic Needle Network (DNN) approach for the growth complex dendritic microstructures. Using new formulation DNN dynamics equations paraboloid-branches given thickness, one can directly extend to 3D modeling. validate this against known scaling laws and analytical solutions that describe early transient steady-state regimes, respectively. Finally, we compare predictions model in situ X-ray imaging Al-Cu alloy...
For ductile metals, dynamic fracture occurs principally through void nucleation, growth, and coalescence at heterogeneities in the microstructure. Previous experimental research on high purity metals has shown that microstructural features, such as grain boundaries, inclusions, vacancies, heterogeneities, can act initial nucleation sites. In addition, other two-phase materials also highlighted importance of properties a second phase itself determining response overall material. However,...
Historically, metals are cut up and polished to see the structure infer how processing influences evolution. We can now peer into a metal during without destroying it using proton radiography. Understanding link between is important because profoundly affects properties of engineering materials. Synchrotron x-ray radiography has enabled real-time glimpses solidification. However, energies favor examination small volumes low density metals. Here we use high energy for first time image large...
An application of nuclear physics, a facility for using protons flash radiography, has been developed at the Los Alamos Neutron Science Center (LANSCE). Protons have proven far superior to high energy x-rays radiography because their long mean free path, good position resolution, and low scatter background. Although this is primarily used studying very fast phenomena such as explosive driven experiments, it finding increasing other fields, tomography static objects, phase changes in...
Abstract We follow an Al-12 at. pct Cu alloy sample from the liquid state to mechanical failure, using in situ X-ray radiography during directional solidification and tensile testing, as well three-dimensional computed tomography of microstructure before after testing. The processing stage is simulated with a multi-scale dendritic needle network model, micromechanical behavior solidified voxelized data elasto-viscoplastic fast Fourier transform model. This study demonstrates feasibility...
High energy electrons have been used to investigate an extension of transmission electron microscopy. This technique, high microscopy (THEEM), provides two additional capabilities First, are more penetrating than low electrons, and thus, they able image through thicker samples. Second, the accelerating mode a radio-frequency linear accelerator fast exposures, down 1 ps, which ideal for flash radiography, making THEEM well suited study evolution material processes under dynamic conditions....
The formation of Al nanocrystals from an amorphous Al92Sm8 alloy involves kinetic phenomena with very different characteristic length and timescales, including initial nucleation later growth coarsening. Insight into these processes can be derived the evolution sizes as a function time. Synchrotron small angle x-ray scattering (SAXS) experiments provide information about nanocrystal size distribution, particularly at times after has reached saturation. Accurately interpreting distribution...
In situ characterization techniques are now affording direct interrogation of opaque materials during synthesis and processing. this work, synchrotron X-ray radiography tomography were performed at Argonne National Laboratory’s Advanced Photon Source to monitor metallic alloys melting solidification. radiographs microstructure evolution in Al-7at.%Cu continuous heating cooling obtained; the influence rate on was also explored. results solidification progression mushy zone presented. These...