Observation of recovery and recrystallization in high-purity aluminum measured with forward modeling analysis of high-energy diffraction microscopy

We have used high energy x-ray diffraction microscopy (HEDM) to study annealing behavior in high purity aluminum. In-situ measurements were carried out at Sector 1 of the Advanced Photon Source. The microstructure in a small sub-volume of a 1 mm diameter wire was mapped in the as-received state and after two differential anneals. Forward modeling analysis reveals three dimensional grain structures and internal orientation distributions inside grains. The analysis demonstrates increased ordering with annealing as well as persistent low angle internal boundaries. Grains that grow from disordered regions are resolution limited single crystals. Together with this recovery behavior, we observe subtle motions of some grain boundaries due to annealing.

Download Full-text

Tests of microstructure reconstruction by forward modeling of high energy X-ray diffraction microscopy data

Powder Diffraction ◽

10.1154/1.3427328 ◽

2010 ◽

Vol 25 (2) ◽

pp. 132-137 ◽

Cited By ~ 13

Author(s):

C. M. Hefferan ◽

S. F. Li ◽

J. Lind ◽

R. M. Suter

Keyword(s):

Near Field ◽

Simulated Data ◽

Forward Modeling ◽

High Energy ◽

Data Sets ◽

Geometric Accuracy ◽

X Ray Diffraction ◽

Detector Resolution ◽

X Ray ◽

Diffraction Microscopy

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 the simulated and reconstructed microstructures is examined with consideration to both crystallographic orientation and spatial geometric accuracy. To probe the dependence of results on experimental parameters, simulated data sets use two different detector configurations and different simulated experimental protocols; in each case, the parameters mimic the experimental geometry used at Advanced Photon Source beamline 1-ID. Results indicate that element orientations are distinguishable to less than 0.1°, while spatial geometric accuracy is limited by the detector resolution.

Download Full-text

The Population of Twin Related Boundaries in High Purity Nickel as Measured with Near-Field High Energy X-Ray Diffraction Microscopy

8th International Symposium on Superalloy 718 and Derivatives ◽

10.1002/9781119016854.ch70 ◽

2014 ◽

pp. 885-896 ◽

Cited By ~ 1

Author(s):

C.M. Hefferan ◽

S.F. Li ◽

J. Lind ◽

R Pokharel ◽

U. Lienert ◽

...

Keyword(s):

High Purity ◽

Near Field ◽

High Energy ◽

X Ray Diffraction ◽

X Ray ◽

Diffraction Microscopy

Download Full-text

The Population of Twin Related Boundaries in High Purity Nickel as Measured with Near-Field High Energy X-Ray Diffraction Microscopy

10.7449/2014/superalloys_2014_885_896 ◽

2014 ◽

Author(s):

C. Hefferan ◽

A. Rollett ◽

J. Lind ◽

R. Pokharel ◽

R. Suter ◽

...

Keyword(s):

High Purity ◽

Near Field ◽

High Energy ◽

X Ray Diffraction ◽

X Ray ◽

Diffraction Microscopy

Download Full-text

Probing Microstructure Dynamics With X-Ray Diffraction Microscopy

Journal of Engineering Materials and Technology ◽

10.1115/1.2840965 ◽

2008 ◽

Vol 130 (2) ◽

Cited By ~ 22

Author(s):

R. M. Suter ◽

C. M. Hefferan ◽

S. F. Li ◽

D. Hennessy ◽

C. Xiao ◽

...

Keyword(s):

Three Dimensional ◽

Forward Modeling ◽

X Ray Diffraction ◽

X Ray ◽

Modeling Analysis ◽

Wide Line ◽

Diffraction Microscopy ◽

Focused Beam ◽

Photon Source

We describe our recent work on developing X-ray diffraction microscopy as a tool for studying three dimensional microstructure dynamics. This is a measurement technique that is demanding of experimental hardware and presents a challenging computational problem to reconstruct the sample microstructure. A dedicated apparatus exists at beamline 1-ID of the Advanced Photon Source for performing these measurements. Submicron mechanical precision is combined with focusing optics that yield ≈2μmhigh×1.3mm wide line focused beam at 50keV. Our forward modeling analysis approach generates diffraction from a simulated two dimensional triangular mesh. Each mesh element is assigned an independent orientation by optimizing the fit to experimental data. The method is computationally demanding but is adaptable to parallel computation. We illustrate the state of development by measuring and reconstructing a planar section of an aluminum polycrystal microstructure. An orientation map of ∼90 grains is obtained along with a map showing the spatial variation in the quality of the fit to the data. Sensitivity to orientation variations within grains is on the order of 0.1deg. Volumetric studies of the response of microstructures to thermal or mechanical treatment will soon become practical. It should be possible to incorporate explicit treatment of defect distributions and to observe their evolution.

Download Full-text

High-purity Ge x-ray detectors: Sensitivity factors and usefulness

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100136350 ◽

1990 ◽

Vol 48 (2) ◽

pp. 548-548

Author(s):

E. B. Steel

Keyword(s):

High Purity ◽

High Energy ◽

Quantitative Chemical Analysis ◽

Detector Performance ◽

X Ray ◽

Detector Sensitivity ◽

Specimen Holder ◽

Many Instruments ◽

Charge Resolution ◽

Sensitivity Factors

High Purity Germanium (HPGe) x-ray detectors are now commercially available for the analytical electron microscope (AEM). The detectors have superior efficiency at high x-ray energies and superior resolution compared to traditional lithium-drifted silicon [Si(Li)] detectors. However, just as for the Si(Li), the use of the HPGe detectors requires the determination of sensitivity factors for the quantitative chemical analysis of specimens in the AEM. Detector performance, including incomplete charge, resolution, and durability has been compared to a first generation detector. Sensitivity factors for many elements with atomic numbers 10 through 92 have been determined at 100, 200, and 300 keV. This data is compared to Si(Li) detector sensitivity factors.The overall sensitivity and utility of high energy K-lines are reviewed and discussed. Many instruments have one or more high energy K-line backgrounds that will affect specific analytes. One detector-instrument-specimen holder combination had a consistent Pb K-line background while another had a W K-line background.

Download Full-text