Effects of microstructure on the elastic properties of selected Ta₂O₅--Eu₂O₃ compositions.

Thesis/Dissertation · Wed Jun 01 04:00:00 EDT 1977

DOI:https://doi.org/10.2172/6694051· OSTI ID:6694051

Malarkey, Christopher John ^[1]

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1. Iowa State Univ., Ames, IA (United States)

Elastic properties and internal friction of selected compositions of tantala-doped monoclinic europia were studied at temperatures up to 1500°C using the sonic resonance technique. Unit cell parameters between 25C and 1000°C for monoclinic Eu₂O₃ were calculated from high temperature x-ray diffractometer data. Large-grained monoclinic specimens having less than 6.0 Ta cation percent substitution exhibited anomalous elastic behavior when thermally cycled. Compositions above this addition level exhibited linear elastic behavior. Internal friction values also varied abnormally with grain size, composition, and temperature. The anomalous behavior was attributed to microcracking caused by thermal expansion anisotropies. The critical grain size was found to be approximately 14 μm. The high temperature diffractometry measurements supported the postulate that the grain coarsening effect associated with sintered monoclinic Eu₂O₃ is the controlling factor for microcracking.

• Research Organization: Ames Lab., Ames, IA (United States)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6694051
• Report Number(s): IS-T--762
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ACOUSTIC MEASUREMENTS
CHALCOGENIDES
CHEMICAL COMPOSITION
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DIFFRACTION
ELASTICITY
EUROPIUM COMPOUNDS
EUROPIUM OXIDES
EXPANSION
FRICTION
GRAIN SIZE
MECHANICAL PROPERTIES
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RARE EARTH COMPOUNDS
SCATTERING
SIZE
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
THERMAL EXPANSION
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION