High temperature deformation of MgO

Technical Report · Sat Nov 01 04:00:00 EST 1975

DOI:https://doi.org/10.2172/7357409· OSTI ID:7357409

Dokko, C

The deformation and recovery of both single crystals ((100), (110), (111) and Ni-doped (100)) and fully dense polycrystals (with grain sizes ranging from 4 to 160 ..mu..m) of MgO were studied under compressive stress-strain and creep testing conditions at 1200/sup 0/C (0.48 Tm) and 1400/sup 0/C (0.55 Tm). Emphasis was placed on the aspects relevant to ductility such as recovery contribution and the role of grain boundaries. No polycrystals were harder than a (111) crystal, nor softer than a (100) crystal, which represented dislocation glide on the more difficult and less difficult slip planes, respectively. Plastic anisotropy between these slip planes decreased and polycrystaline ductility increased with decreasing strain rate as well as increasing temperature. Simultaneous activation of all five independent slip systems did not lead to a large ductility. A maximum ductility was observed for the smallest grain size under given testing conditions. In addition to slip on both planes and dislocation-climb-aided accommodation, intergranular separation is suggested as a mode of accommodation, although it was accompanied by weakening effects. Significance of grain boundary nature, per se, was indicated by variability of the mechanical behavior as a function of prior annealing history for the same grain size. (auth)

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7357409
• Report Number(s): LBL-3979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALKALINE EARTH METAL COMPOUNDS
ANISOTROPY
ANNEALING
CHALCOGENIDES
CRYSTAL STRUCTURE
CRYSTALS
DEFORMATION
DENSITY
DUCTILITY
FAILURES
FRACTURES
GRAIN SIZE
HEAT TREATMENTS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MECHANICAL PROPERTIES
MICROSTRUCTURE
MONOCRYSTALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLASTICITY
POLYCRYSTALS
SIZE
SLIP
STRAINS
STRESSES
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
VERY HIGH TEMPERATURE