Abstract
Two methods are presented for the analysis of oxygen tracer isotope “double oxidation” experiments. Mass balance criteria are presented for inferring oxide growth mechanisms from the oxygen isotope profile. For the case of inward growing scales, a diffusion model is presented which describes the tracer distribution as a function of lattice and grain boundary diffusivities, grain size and the parabolic growth rate.
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Abbreviations
- J 18 y :
-
Flux of tracer down the grain boundary
- J 16 y :
-
Flux of O-16 down the grain boundary
- J TOT y :
-
Total flux of oxygen down the grain boundary
- J 18 x :
-
Flux of tracer out of grain boundary
- J 16 x :
-
Flux of O-16 into grain boundary
- D b :
-
Grain boundary diffusion coefficient
- D :
-
Lattice diffusion coefficient
- Δμ 0 :
-
Oxygen chemical potential change across the oxide scale
- Y :
-
Total oxide thickness
- Y old :
-
Thickness of oxide formed during O-16 oxidation
- Y new :
-
Thickness of oxide formed during O-18 oxidation
- Y innew :
-
Thickness of oxide formed during O-18 oxidation due to inward anion diffusion
- Y outnew :
-
Thickness of oxide formed during O-18 oxidation due to outward cation diffusion
- K p :
-
Parabolic rate constant
- t :
-
O-18 oxidation time
- τ :
-
O-16 oxidation time
- φ y :
-
Tracer concentration in grain boundary at depthy
- C :
-
Tracer concentration in the grain
- C i :
-
Initial tracer concentration in grain
- C g :
-
Average tracer concentration in oxide grain
- ¯C :
-
Average tracer concentration at depthy
- C max :
-
Maximum tracer concentration in the oxide scale
- C s :
-
Tracer concentration in gas during O-18 oxidation
- δ :
-
Grain boundary width
- r :
-
Grain size
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Basu, S.N., Halloran, J.W. Tracer isotope distribution in growing oxide scales. Oxid Met 27, 143–155 (1987). https://doi.org/10.1007/BF00667055
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DOI: https://doi.org/10.1007/BF00667055