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Title: Microstrain temperature evolution in beta-eurcryptite ceramics: Measurement and model

Abstract

Mechanisms of microcracking and stress release in {beta}-eucryptite ceramics were investigated by applying a combination of neutron diffraction (ND), dilatometry and the Integrity Factor Model (IFM). It was observed that the macroscopic thermal expansion of solid samples closely follows the lattice thermal expansion as a function of temperature, and both are dominated by microcracks closing (during heating) and opening (during cooling). Analogous experiments on powders showed that the stresses that manifest peak shift are indeed relieved by comminution, and that the resulting lattice thermal expansion can be considered as unconstrained. By means of Rietveld refinement of the ND data, the evolution with temperature of peak width parameters linked to strain distributions along the basal, pyramidal and axial planes could also be extracted. The peak width parameters S{sub HKL} correlated well with the strains calculated by peak shift and with the model results. Furthermore, while the peak shifts showed that the powders are basically stress free, the S{sub HKL} showed a strong evolution of the peak width. Powders carry, therefore, a measurable strain distribution inside the particles, owing to the thermal expansion anisotropy of the crystallites. The IFM allowed this behavior to be rationalized, and the effect of microcracking on thermalmore » expansion to be quantified. Experimental data allowed accurate numerical prediction of microcracking on cooling and of the evolution of microstresses. They also allowed the derivation of the material elastic modulus from bulk thermal expansion curves through the IFM concept. Ultrasound resonance measurements of the elastic modulus strongly support these theoretical predictions.« less

Authors:
 [1];  [2];  [3];  [1];  [2];  [2]
  1. Corning, Inc
  2. ORNL
  3. Purdue University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1050315
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 60; Journal Issue: 12; Journal ID: ISSN 1359-6454
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; CERAMICS; COMMINUTION; DILATOMETRY; DISTRIBUTION; FORECASTING; HEATING; NEUTRON DIFFRACTION; OPENINGS; RESONANCE; STRAINS; STRESSES; THERMAL EXPANSION; beta-eucryptite; microcracking; neutron diffraction; intergrity factor model; Rietveld refinement

Citation Formats

Bruno, Giovanni, Garlea, Vasile O, Muth, Joseph T., Efremov, Alexander, Watkins, Thomas R, and Shyam, Amit. Microstrain temperature evolution in beta-eurcryptite ceramics: Measurement and model. United States: N. p., 2012. Web. doi:10.1016/j.actamat.2012.04.033.
Bruno, Giovanni, Garlea, Vasile O, Muth, Joseph T., Efremov, Alexander, Watkins, Thomas R, & Shyam, Amit. Microstrain temperature evolution in beta-eurcryptite ceramics: Measurement and model. United States. https://doi.org/10.1016/j.actamat.2012.04.033
Bruno, Giovanni, Garlea, Vasile O, Muth, Joseph T., Efremov, Alexander, Watkins, Thomas R, and Shyam, Amit. 2012. "Microstrain temperature evolution in beta-eurcryptite ceramics: Measurement and model". United States. https://doi.org/10.1016/j.actamat.2012.04.033.
@article{osti_1050315,
title = {Microstrain temperature evolution in beta-eurcryptite ceramics: Measurement and model},
author = {Bruno, Giovanni and Garlea, Vasile O and Muth, Joseph T. and Efremov, Alexander and Watkins, Thomas R and Shyam, Amit},
abstractNote = {Mechanisms of microcracking and stress release in {beta}-eucryptite ceramics were investigated by applying a combination of neutron diffraction (ND), dilatometry and the Integrity Factor Model (IFM). It was observed that the macroscopic thermal expansion of solid samples closely follows the lattice thermal expansion as a function of temperature, and both are dominated by microcracks closing (during heating) and opening (during cooling). Analogous experiments on powders showed that the stresses that manifest peak shift are indeed relieved by comminution, and that the resulting lattice thermal expansion can be considered as unconstrained. By means of Rietveld refinement of the ND data, the evolution with temperature of peak width parameters linked to strain distributions along the basal, pyramidal and axial planes could also be extracted. The peak width parameters S{sub HKL} correlated well with the strains calculated by peak shift and with the model results. Furthermore, while the peak shifts showed that the powders are basically stress free, the S{sub HKL} showed a strong evolution of the peak width. Powders carry, therefore, a measurable strain distribution inside the particles, owing to the thermal expansion anisotropy of the crystallites. The IFM allowed this behavior to be rationalized, and the effect of microcracking on thermal expansion to be quantified. Experimental data allowed accurate numerical prediction of microcracking on cooling and of the evolution of microstresses. They also allowed the derivation of the material elastic modulus from bulk thermal expansion curves through the IFM concept. Ultrasound resonance measurements of the elastic modulus strongly support these theoretical predictions.},
doi = {10.1016/j.actamat.2012.04.033},
url = {https://www.osti.gov/biblio/1050315}, journal = {Acta Materialia},
issn = {1359-6454},
number = 12,
volume = 60,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}