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Multiscale Plastic Deformation Near Fatigue Crack From Diffraction

Rozaliya I. Barabash 1,2Yunan Sun 2G E. Ice 1Peter Liaw 2Hahn Choo 1,2David Brown 2

1. Oak Ridge National Laboratory (ORNL), One bethel Valley Road, Oak Ridge, TN 37932, United States
2. University of Tennessee (UTK), Knoxville, TN, United States


The multiscale plastic deformation in the vicinity of the crack tip was studied with neutron and x-ray microbeam diffraction. The results help to understand the overload effect, which induced large plastic deformation causing hierarchical dislocation arrangement around the crack tip. From neutron diffraction measurement anisotropic line broadening was observed in front of the crack tip. Furthermore, Laue patterns obtained from microbeam diffraction at different locations near the crack, provide a better spatial resolution and show alternating regions with high and low dislocation density. Orientation dependence on (hkl) of both strains and line broadening was observed indicating non random dislocation arrangement. Dislocation density and arrangement was evaluated from the line width and profile behavior for several crystallographic families. Lattice strains were analyzed by GSAS. Comparison of the results obtained with GSAS and line profile analysis allowed to understand the change of hierarchical dislocation density distribution and strain in different plastic zones. Overall, the dislocation density was found to decrease with the distance from the crack tip.


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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium H, by Rozaliya I. Barabash
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-24 16:00
Revised:   2009-06-07 00:44