skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Multivariate Statistical Approach to Electron Back Scattered Diffraction.

Abstract

Abstract not provided.

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1148184
Report Number(s):
SAND2007-3064J
523325
DOE Contract Number:
DE-AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Ultramicroscopy; Related Information: Proposed for publication in Ultramicroscopy.
Country of Publication:
United States
Language:
English

Citation Formats

Brewer, Luke N., Kotula, Paul Gabriel, and Michael, Joseph R. Multivariate Statistical Approach to Electron Back Scattered Diffraction.. United States: N. p., 2007. Web.
Brewer, Luke N., Kotula, Paul Gabriel, & Michael, Joseph R. Multivariate Statistical Approach to Electron Back Scattered Diffraction.. United States.
Brewer, Luke N., Kotula, Paul Gabriel, and Michael, Joseph R. Tue . "Multivariate Statistical Approach to Electron Back Scattered Diffraction.". United States. doi:.
@article{osti_1148184,
title = {Multivariate Statistical Approach to Electron Back Scattered Diffraction.},
author = {Brewer, Luke N. and Kotula, Paul Gabriel and Michael, Joseph R.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {Ultramicroscopy},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • The ability to map plastic deformation around high strain gradient microstructural features is central in studying phenomena such as fatigue and stress corrosion cracking. A method for the visualization of plastic deformation in electron back-scattered diffraction (EBSD) data has been developed and is described in this article. This technique is based on mapping the intragrain misorientation in polycrystalline metals. The algorithm maps the scalar misorientation between a local minimum misorientation reference pixel and every other pixel within an individual grain. A map around the corner of a Vickers indentation in 304 stainless steel was used as a test case. Severalmore » algorithms for EBSD mapping were then applied to the deformation distributions around air fatigue and stress corrosion cracks in 304 stainless steel. Using this technique, clear visualization of a deformation zone around high strain gradient microstructural features (crack tips, indentations, etc.) is possible with standard EBSD data.« less
  • The Electron Back-Scattered Diffraction (EBSD) technique is in its infancy and is a highly promising area of development. Use of EBSD has been predominantly for the determination of crystallographic textures. Other applications have also been considered, which include: crystal structure determination, phase determination, grain boundary studies and both elastic and plastic deformation measurement. Although it has been acknowledged that an important use of the EBSD could be in the measurement of recrystallization and its kinetics there are a number of inherent problems with such measurements using EBSD. These problems include the ability of the system to index deformed microstructures evenmore » those on a fine scale, the difficulties of analyzing patterns in the region of grain boundaries and the problems of sample preparation which is critical in the quality of the diffraction patterns obtained. The aim of the present study is to determine whether it is possible to measure the volume fraction recrystallized using EBSP of partially recrystallized stainless steel. This has been done by investigation of the quality of matching between the observed and calculated diffraction patterns, and the quality of the observed patterns measured in terms of their contrast. The material used was stainless steel 316L.« less
  • Exposure of metals and alloys to high temperatures leads to the formation of oxide scales. Characterizing the nature of the scale is of considerable importance to the steel manufacturers, who are under continual pressure to improve surface finish. Scale properties are also of interest because of the effect on friction and heat transfer during hot working operations, and the resultant wear of tooling or work rolls. Oxidation of pure iron is well documented and has lead to the classical three layer scale characterization. Hot working operations break up the classical three layer scale and make characterization of the individual componentsmore » of the scale difficult. Identification of the individual components simply by their layer position is no longer reliable since the layers have been disrupted by the hot working process. Scale microstructures become further complicated on cooling as the wuestite decomposes to magnetite at temperatures below 570 C. The resultant scale microstructures are therefore complex on a sub-micron scale. These secondary and tertiary scales must be removed before subsequent processing, such as cold rolling or wire drawing and the mechanical properties of the scale layers are important factors when considering descalability. For example, hematite is much harder than magnetite and wuestite, thus magnetite scales are more brittle and therefore easier to remove than scales containing wuestite.with this in mind it is necessary to develop a reliable technique for the characterization of these scales and their microstructures with respect to developing an ideal scale for easy removal, without sacrificing the mechanical properties of the product. Furthermore a reliable method of characterizing the scale development along the rolling mill would be useful in charting the scale growth and re-growth behavior between passes and may lead to the development of an ideal rolling schedule for the formation of an easily removed scale. This paper discusses the characterization of these scales by electron back scattered diffraction.« less
  • In permanent magnets based on the Sm{sub 2}Co{sub 17} phase, the high coercivity depends on the presence of a complex microstructure, consisting of a Sm{sub 2}(Co,Fe){sub 17} cell phase, a cell boundary phase Sm(Co,Cu){sub 5}, and a Zr-rich platelet or lamellae phase. The aim of this work is to use electron back scatter diffraction (EBSD) in order to identify the different phases present in the isotropic magnets produced from cast alloys with the composition of Sm(Co{sub bal}Fe{sub 0.2}Cu{sub 0.1}Zr{sub x}){sub 8}, where x = 0, 0.02, or 0.06, and correlate them with the different phases observed in scanning electron microscopymore » (SEM) images. Due to the combination of careful surface preparation and high resolution microscopy, it was possible to observe the cellular structure characteristic of the 2:17 magnets in the SEM images. Until now, only transmission electron microscopy (TEM) had been used. Composition maps, energy dispersive spectroscopy (EDS), and EBSD measurements were used for doing the phase identification.« less
  • Here, spherical nanoindentation combined with electron back-scattered diffraction has been employed to characterize the grain-scale elastic and plastic anisotropy of single crystal alpha-Ti of two different compositions (in two different titanium alloys). Data analyses protocols needed to reliably extract the desired properties of interest are extended and demonstrated in this paper. Specifically, the grain-scale mechanical response is extracted in the form of indentation stress-strain curves for commercially pure (CP-Ti) alpha-Ti and alloyed (Ti-64) titanium from measurements on polycrystalline samples. The results are compared with responses of single crystals and nanoindentation tests (hardness and modulus) from the literature, and the measuredmore » indentation moduli are validated using crystal-elastic finite element simulations. The results obtained in this study show that (i) it is possible to characterize reliably the elastic and plastic anisotropy of alpha-Ti (hcp) of varying alloying contents with spherical nanoindentation stress-strain curves, (ii) the indentation modulus of alpha-Ti-64 is 5–10% less than CP-Ti, and (iii) the indentation yield strength of alpha-Ti-64 is 50–80% higher than CP-Ti.« less