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Creep of Polycrystalline MgO‐FeO‐Fe 2 O 3 Solid Solutions
Author(s) -
TREMPER R. T.,
GIDDINGS R. A.,
HODGE J. D.,
GORDON R. S.
Publication year - 1974
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1974.tb11373.x
Subject(s) - creep , materials science , activation energy , crystallite , dopant , grain boundary , grain size , lattice diffusion coefficient , grain boundary diffusion coefficient , diffusion creep , doping , diffusion , mineralogy , analytical chemistry (journal) , composite material , metallurgy , thermodynamics , effective diffusion coefficient , microstructure , chemistry , medicine , physics , optoelectronics , chromatography , magnetic resonance imaging , radiology
Steady‐state creep experiments were performed on hot‐pressed polycrystalline MgO doped with Fe. Dead‐load 4‐point bend creep tests were conducted at stresses of 26 to 270 kg/cm 2 , at temperatures of 1250° to 1450°C, in O 2 partial pressures of 1 to 10 −9 atm, on specimens with grain sizes of 10 to 65 μm. Viscous steady‐state creep was always observed when the grain size was stable. Experiments at variable P O2 's and temperatures were used to identify regimes of high (117 ± 10 kcal/mol) and low (81 ± 5 kcal/mol) activation energy. In the latter, creep rates were nearly independent of Fe dopant concentration and P O2 , whereas in the former creep rates were enhanced by increasing P O2 's and Fe dopant levels. The high‐ and low‐activation‐energy regimes were interpreted as diffusional creep controlled primarily by Mg lattice diffusion and O grain‐boundary diffusion, respectively.