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Fracture of a textured anisotropic ceramic

Zimmerman, M. H. and Baskin, D. M. and Faber, K. T. and Fuller, E. R., Jr. and Allen, A. J. and Keane, D. T. (2001) Fracture of a textured anisotropic ceramic. Acta Materialia, 49 (16). pp. 3231-3242. ISSN 1359-6454. https://resolver.caltech.edu/CaltechAUTHORS:20140908-181322226

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Abstract

The role of crystallographic texture in determining the fracture behavior of a highly anisotropic ceramic, iron titanate, has been examined. By exploiting the anisotropy in its single crystal magnetic susceptibility, crystallographically textured and untextured iron titanate microstructures were formed by gelcasting in the presence and absence of a strong magnetic field, respectively. The magnetic field-assisted processing imparted a fiber-like texture to the processed ceramic material in which the crystallographic b-axes of the grains aligned parallel to the applied field. Triaxial residual stress and lattice parameter measurements showed that both the untextured and textured materials had undergone significant stress–relaxation, presumably due to spontaneous microcracking. Further, ‘aggregates’ of non-textured material were discovered within textured material that led to a population of meso-scale cracks (meso-cracks) in the microstructure oriented normal to the direction of alignment. Both crack populations were examined using a finite element simulation and confirmed by small angle neutron scattering measurements, and for meso-cracks, by X-ray tomography. Bend strength and R-curve behavior were evaluated as a function of texture and orientation in the magnetically processed materials. Strengths remained within 20% of that of the control material, except for one orientation, for which the strength decreased with increasing degree of texture due to favorably oriented meso-cracks. The R-curve behavior was highly anisotropic, with the peak fracture toughness of the magnetically processed material ranging from approximately equal to 2.5 times that of the control material. Additionally, the peak fracture toughness of each orientation increased with the degree of texture. Anisotropic fracture properties were related to interactions between the test crack and the population of meso-cracks.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/S1359-6454(01)00224-5DOIArticle
http://www.sciencedirect.com/science/article/pii/S1359645401002245PublisherArticle
Additional Information:© 2001 Acta Materialia Inc. Published by Elsevier. (Received 29 March 2001; accepted 23 May 2001). Funding for this work was provided by the National Science Foundation under Grant No. DMR-9800257. We are indebted to the late Professor Jerome B. Cohen for suggesting the tomography experiment and to Professor William Halperin of the Department of Physics and Astronomy, Northwestern University, whose magnet was used for these studies. Parts of this research were conducted at the National Synchrotron Light Source, Brookhaven National Laboratory, which is supported by the US Department of Energy, Division of Materials Sciences and Division of Chemical Sciences (DOE contract number DE-AC02-76CH00016). Thank you to John Dunsmuir for the excellent XMT beamline X2B at NSLS. We acknowledge the NIST Center for Neutron Research for the use of neutron beam facilities.
Funders:
Funding AgencyGrant Number
NSFDMR-9800257
Department of Energy (DOE)DE-AC02-76CH00016
Subject Keywords:Ceramics; Fracture & fracture toughness; Small angle neutron scattering; Texture
Issue or Number:16
Record Number:CaltechAUTHORS:20140908-181322226
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140908-181322226
Official Citation:M.H Zimmerman, D.M Baskin, K.T Faber, E.R Fuller Jr., A.J Allen, D.T Keane, Fracture of a textured anisotropic ceramic, Acta Materialia, Volume 49, Issue 16, 20 September 2001, Pages 3231-3242, ISSN 1359-6454, http://dx.doi.org/10.1016/S1359-6454(01)00224-5. (http://www.sciencedirect.com/science/article/pii/S1359645401002245)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49389
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:09 Sep 2014 17:50
Last Modified:03 Oct 2019 07:13

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