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Title: Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening

Abstract

In order to investigate their microcracking behaviour, the microstructures of several β-eucryptite ceramics, obtained from glass precursor and cerammed to yield different grain sizes and microcrack densities, were characterized by laboratory and synchrotron x-ray refraction and tomography. Here, results were compared with those obtained from scanning electron microscopy (SEM). In SEM images, the characterized materials appeared fully dense but computed tomography showed the presence of pore clusters. Uniaxial tensile testing was performed on specimens while strain maps were recorded and analyzed by Digital Image Correlation (DIC). X-ray refraction techniques were applied on specimens before and after tensile testing to measure the amount of the internal specific surface (i.e., area per unit volume). X-ray refraction revealed that (a) the small grain size (SGS) material contained a large specific surface, originating from the grain boundaries and the interfaces of TiO 2 precipitates; (b) the medium (MGS) and large grain size (LGS) materials possessed higher amounts of specific surface compared to SGS material due to microcracks, which decreased after tensile loading; (c) the precursor glass had negligible internal surface. The unexpected decrease in the internal surface of MGS and LGS after tensile testing is explained by the presence of compressive regions in themore » DIC strain maps and further by theoretical arguments. It is suggested that while some microcracks merge via propagation, more close mechanically, thereby explaining the observed X-ray refraction results. Lastly, the mechanisms proposed would allow the development of a strain hardening route in ceramics.« less

Authors:
 [1];  [2];  [3];  [3];  [4];  [5];  [6];  [7]; ORCiD logo [4]; ORCiD logo [8]
  1. Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (Germany)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Connecticut, Storrs, CT (United States). Mechanical Engineering Dept.
  3. Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (Germany)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  5. Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (German; Technical Univ., Berlin (Germany). Inst. for Materials
  6. Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (Germany); Thermo Fisher Scientific, Berlin (Germany)
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Rolls Royce LG Fuel Cell System Inc., North Canton, OH (United States). Reliability Division
  8. Bundesanstalt fur Materialforschung und -prufung (BAM), Berlin (Germany). Inst. of Physics and Astronomy
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1423102
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 144; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Beta-eucryptite; Microcracked ceramics; X-ray refraction; Tensile load; Strain hardening

Citation Formats

Müller, B. R., Cooper, R. C., Lange, A., Kupsch, A., Wheeler, Matthew R., Hentschel, M. P., Staude, A., Pandey, Amit, Shyam, Amit, and Bruno, Giovanni. Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening. United States: N. p., 2017. Web. doi:10.1016/j.actamat.2017.10.030.
Müller, B. R., Cooper, R. C., Lange, A., Kupsch, A., Wheeler, Matthew R., Hentschel, M. P., Staude, A., Pandey, Amit, Shyam, Amit, & Bruno, Giovanni. Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening. United States. doi:10.1016/j.actamat.2017.10.030.
Müller, B. R., Cooper, R. C., Lange, A., Kupsch, A., Wheeler, Matthew R., Hentschel, M. P., Staude, A., Pandey, Amit, Shyam, Amit, and Bruno, Giovanni. Wed . "Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening". United States. doi:10.1016/j.actamat.2017.10.030.
@article{osti_1423102,
title = {Stress-induced microcrack density evolution in β-eucryptite ceramics: Experimental observations and possible route to strain hardening},
author = {Müller, B. R. and Cooper, R. C. and Lange, A. and Kupsch, A. and Wheeler, Matthew R. and Hentschel, M. P. and Staude, A. and Pandey, Amit and Shyam, Amit and Bruno, Giovanni},
abstractNote = {In order to investigate their microcracking behaviour, the microstructures of several β-eucryptite ceramics, obtained from glass precursor and cerammed to yield different grain sizes and microcrack densities, were characterized by laboratory and synchrotron x-ray refraction and tomography. Here, results were compared with those obtained from scanning electron microscopy (SEM). In SEM images, the characterized materials appeared fully dense but computed tomography showed the presence of pore clusters. Uniaxial tensile testing was performed on specimens while strain maps were recorded and analyzed by Digital Image Correlation (DIC). X-ray refraction techniques were applied on specimens before and after tensile testing to measure the amount of the internal specific surface (i.e., area per unit volume). X-ray refraction revealed that (a) the small grain size (SGS) material contained a large specific surface, originating from the grain boundaries and the interfaces of TiO2 precipitates; (b) the medium (MGS) and large grain size (LGS) materials possessed higher amounts of specific surface compared to SGS material due to microcracks, which decreased after tensile loading; (c) the precursor glass had negligible internal surface. The unexpected decrease in the internal surface of MGS and LGS after tensile testing is explained by the presence of compressive regions in the DIC strain maps and further by theoretical arguments. It is suggested that while some microcracks merge via propagation, more close mechanically, thereby explaining the observed X-ray refraction results. Lastly, the mechanisms proposed would allow the development of a strain hardening route in ceramics.},
doi = {10.1016/j.actamat.2017.10.030},
journal = {Acta Materialia},
number = C,
volume = 144,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}

Journal Article:
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