A5006490230- Microstructure and mechanical properties
- Microstructure and Mechanical Properties of Steels
- Electron and X-Ray Spectroscopy Techniques
- Aluminum Alloy Microstructure Properties
- High Temperature Alloys and Creep
- Advanced X-ray Imaging Techniques
- Composite Material Mechanics
- Advanced Electron Microscopy Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- X-ray Diffraction in Crystallography
- Advanced Materials Characterization Techniques
- Fatigue and fracture mechanics
- Metallurgy and Material Forming
- Nuclear reactor physics and engineering
- nanoparticles nucleation surface interactions
- Magnetic Properties and Applications
- Semiconductor materials and interfaces
- Optical measurement and interference techniques
- Particle Accelerators and Free-Electron Lasers
- Non-Destructive Testing Techniques
- Force Microscopy Techniques and Applications
- Chemical Synthesis and Characterization
- Mechanical Failure Analysis and Simulation
- Hydraulic Fracturing and Reservoir Analysis
- Nuclear Physics and Applications
Carnegie Mellon University
2009-2023
RJ Lee Group (United States)
2014-2019
Lawrence Livermore National Laboratory
2014
Grain boundary velocity has been believed to be correlated curvature, and this is an important relationship for modeling how polycrystalline materials coarsen during annealing. We determined the velocities curvatures of approximately 52,000 grain boundaries in a nickel polycrystal using three-dimensional orientation maps measured by high-energy diffraction microscopy before after annealing at 800°C. Unexpectedly, were uncorrelated. Instead, we found strong correlations between five...
The changes in both the grain boundary area and energy that occur during growth have been measured polycrystalline Ni using high diffraction microscopy. In addition to reduction of area, average decreases as higher boundaries are replaced by lower boundaries. This dissipation mechanism influences migration might explain absence a correlation between curvature velocity. Classical studies isotropic polycrystals based on idea (GB) is driven product GB curvature. [1,2] While support for this...
The evolution of the crystallographic orientation field in a polycrystalline sample copper is mapped three dimensions as tensile strain applied. Using forward-modeling analysis high-energy X-ray diffraction microscopy data collected at Advanced Photon Source, ability to track intragranular variations demonstrated on an ∼2 µm length scale with ∼0.1° precision. Lattice rotations within grains are tracked between states ∼1° Detailed presented for cross section before and after ∼6% strain....
A microstructure-based capability for forecasting microcrack nucleation in the nickel-based superalloy LSHR is proposed, implemented, and partially verified. Specifically, gradient crystal plasticity applied to finite-element models of experimentally measured, 3D microstructure wherein a known have nucleated along coherent Σ3 boundary. The framework used analyze this particular event conduct an extensive grain boundary analysis study, results which underpin importance that elastic anisotropy...
We have measured and reconstructed via forward modeling a small volume of microstructure high purity, well annealed nickel using energy x-ray diffraction microscopy (HEDM). Statistical distributions characterizing grain orientations, intra-granular misorientations, nearest neighbor misorientations are extracted. Results consistent with recent electron backscatter measurements. Peaks in the misorientation angle distribution at 60 degrees ({Sigma}3) 39 ({Sigma}9) resolution limited widths...
Verification tests of the forward modeling technique for near-field high energy X-ray diffraction microscopy are conducted using two simulated microstructures containing uniformly distributed orientations. Comparison between and reconstructed is examined with consideration to both crystallographic orientation spatial geometric accuracy. To probe dependence results on experimental parameters, data sets use different detector configurations protocols; in each case, parameters mimic geometry...
We describe our recent work on developing X-ray diffraction microscopy as a tool for studying three dimensional microstructure dynamics. This is measurement technique that demanding of experimental hardware and presents challenging computational problem to reconstruct the sample microstructure. A dedicated apparatus exists at beamline 1-ID Advanced Photon Source performing these measurements. Submicron mechanical precision combined with focusing optics yield ≈2μmhigh×1.3mm wide line focused...
A fast Fourier transform (FFT) based spectral algorithm is used to compute the full field mechanical response of polycrystalline microstructures. The distributions in a specific region are determine sensitivity method number surrounding grains through quantification divergence values from largest simulation domain, as successively smaller volumes included simulation. analysis considers mapped 3D structure where location interest taken be particular pair surface that enclose small fatigue...
Comparisons between experiments and simulations of deformation polycrystalline materials reveal some interesting challenges [1]. Addressing first the image processing issues, electron back-scatter diffraction (EBSD) [2] relies heavily on transformations patterns. High energy microscopy (HEDM) [3] also thresholding diffractograms for peak identification [4]. By contrast to standard finite element method, an image-based approach [5] that Fast Fourier Transform (FFT) has started be used...
We have used high energy x-ray diffraction microscopy (HEDM) to study annealing behavior in purity aluminum. In-situ measurements were carried out at Sector 1 of the Advanced Photon Source. The microstructure a small sub-volume mm diameter wire was mapped as-received state and after two differential anneals. Forward modeling analysis reveals three dimensional grain structures internal orientation distributions inside grains. demonstrates increased ordering with as well persistent low angle...
A 3D microstructure, measured by high-energy x-ray diffraction microscopy, is used as an input to a parallelized viscoplastic Fast Fourier Transform code (VPFFT) simulate tensile test. Distributions of strain, damage accumulation, neighbor interactions, and Schmid factor mismatch throughout the microstructure are calculated. These results will form basis direct comparison maps that track plastic deformation in real sample.