Point defects and high-temperature deformation of NiO

Conference · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6198146

Goretta, K C; Routbort, J L

The steady-state flow stress tau/sub s/ in nonstoichiometric NiO single crystals has been measured in the temperature range of 1428 to 1653K with oxygen partial pressures p(O2) between 6 and 1 x 10V Pa. Strain rates epsilon were varied from 1 x 10 V to 2 x 10 T s . Transmission electron microscopy indicates that dislocation climb is the primary mechanism of recovery. Because dislocation climb is diffusion controlled, the data may be described at fixed temperature by epsilon = A tau/sub s//sup n/ p(O2)/sup 1/m/, where n is the stress exponent and m is a parameter that is determined by the dominant atomic defects on each sublattice. At high temperatures and p(O2) > 2 x 10U Pa, n was found to be in agreement with dislocation-climb models; however, n increased at low p(O2) owing to effects of impurities. The values of m are consistent with control of climb rate by diffusion of singly charged oxygen vacancies for low p(O2) and by diffusion of neutral oxygen interstitials for high p(O2). At lower temperatures, the values of n are strongly affected by dislocation/impurity interactions for all p(O2).

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6198146
• Report Number(s): CONF-851217-30; ON: DE86005560
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
DEFORMATION
DISLOCATIONS
ELECTRON MICROSCOPY
LINE DEFECTS
MICROSCOPY
MONOCRYSTALS
NICKEL COMPOUNDS
NICKEL OXIDES
OXIDES
OXYGEN COMPOUNDS
STRAIN RATE
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
VERY HIGH TEMPERATURE