MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Self-Diffusion along Dislocations in Ultra High Purity Iron
Yumiko ShimaYukio IshikawaHiroyuki NittaYoshihiro YamazakiKouji MimuraMinoru IsshikiYoshiaki Iijima
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Volume 43 (2002) Issue 2 Pages 173-177

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Abstract

Self-diffusion along dislocations in ultra high purity iron containing 0.5–1.2 mass ppm carbon, 0.1–1.0 mass ppm nitrogen and 1.8–4.0 mass ppm oxygen has been studied by the radioactive tracer method with the sputter-microsectioning technique. Below 700 K, the self-diffusion coefficient along dislocations has been determined directly from the type C kinetics classified by Harrison, whereas above 800 K it has been obtained by the type B kinetics assuming that the effective radius of dislocation pipe is equal to 5×10−10 m. The temperature dependence of the self-diffusion coefficient along dislocations does not show a linear Arrhenius relation. Below 900 K the Arrhenius plot shows slightly downward curvature. However, above 900 K the self-diffusion coefficient along dislocations increases remarkably with increasing temperature. The value at 900 K is 10−14 m2s−1, while it takes 10−10 m2s−1 at the Curie temperature (1043 K). It seems that the steep increase of the self-diffusion coefficient along dislocations near the Curie temperature is related to the magnetic transformation in ultra high purity iron.

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© 2002 The Japan Institute of Metals and Materials
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