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Intermittent plasticity in individual grains: A study using high energy x-ray diffraction

Cornell Affiliated Author(s)

Author

K. Chatterjee
A.J. Beaudoin
D.C. Pagan
P.A. Shade
H.T. Philipp
M.W. Tate
Sol Gruner
P. Kenesei
J.-S. Park

Abstract

Long-standing evidence suggests that plasticity in metals may proceed in an intermittent fashion. While the documentation of intermittency in plastically deforming materials has been achieved in several experimental settings, efforts to draw connections from dislocation motion and structure development to stress relaxation have been limited, especially in the bulk of deforming polycrystals. This work uses high energy x-ray diffraction measurements to build these links by characterizing plastic deformation events inside individual deforming grains in both the titanium alloy, Ti-7Al, and the magnesium alloy, AZ31. This analysis is performed by combining macroscopic stress relaxation data, complete grain stress states found using far-field high energy diffraction microscopy, and rapid x-ray diffraction spot measurements made using a Mixed-Mode Pixel Array Detector. Changes in the dislocation content within the deforming grains are monitored using the evolution of the full 3-D shapes of the diffraction spot intensity distributions in reciprocal space. The results for the Ti-7Al alloy show the presence of large stress fluctuations in contrast to AZ31, which shows a lesser degree of intermittent plastic flow. © 2019 Author(s).

Date Published

Journal

Structural Dynamics

Volume

6

Issue

1

URL

https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059572687&doi=10.1063%2f1.5068756&partnerID=40&md5=d528db7aaaa2524152bfc9e3a5472800

DOI

10.1063/1.5068756

Group (Lab)

Sol M. Gruner Group

Funding Source

DE-SC0017631
1332208

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