The stoichiometry dependence of the deformation of Co/sub 1-delta/O

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(82)90115-8· OSTI ID:5857672

Routbort, J L

The flow stress tau has been measured for <100> Co/sub 1-delta/O single crystals as a function of strain ..gamma.., between 1000 and 1400/sup 0/C, using strain rates of 5 x 10/sup -6/ to 5 x 10/sup -4/ s/sup -1/, and varying the oxygen partial pressure P/sub O/sub 2// from 10/sup -11/ to 1 atm in order to obtain deviations from stoichiometry delta ranging from approx. =2 x 10/sup -5/ to 10/sup -2/. The tau vs ..gamma.. curves have a pronounced upper yield. The stress then decreases to a minimum tau/sub s/ before additional hardening occurs. A study of the dependence of tau/sub s/ on P/sub O/sub 2// and epsilon indicates that for delta less than or equal to 10/sup -3/ the diffusion of the oxygen vacancy may control the deformation rate. For larger delta, deformation is controlled by diffusion of the oxygen interstitial. The results suggest that the Arrhenius plots are curved, possibly owing to extrinsic effects at the lowest temperature. Serrated flow is observed for small delta at 1000/sup 0/C. The activation energy for deformation is independent of delta, but is stress dependent because the strain-rate sensitivity is a function of temperature.

• Research Organization: Argonne National Lab., IL
• OSTI ID: 5857672
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States); ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
&amp; Refractories-- Mechanical Properties
CHALCOGENIDES
COBALT COMPOUNDS
COBALT OXIDES
CRYSTALS
DEFORMATION
FLOW STRESS
MECHANICAL PROPERTIES
MONOCRYSTALS
OXIDES
OXYGEN COMPOUNDS
STOICHIOMETRY
STRAIN RATE
STRESSES
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE