Enhanced diffusion of Au in γ-Fe by vacancies induced under elevated hydrogen pressure

Yoshihiro Yamazaki, Yoshiaki Iijima, Masuo Okada

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

The diffusion coefficients of Au, DAu*, in γ-Fe in the temperature range from 1263 to 1653 K at 0.1 MPa Ar and from 1207 to 1351 K at 3-5 GPa H2 have been determined by relating the interdiffusion coefficients in single-phase Fe/Fe-Au couples with the Darken-Manning relation. The value of DAu* in γ-Fe at 5 GPa H2 is 2-3 times larger than that at 0.1 MPa Ar. The temperature dependence of D Au* in γ-Fe at 0.1 MPa Ar and at 5 GPa H2 can be expressed as DAu*=8.1-2.3 +3.2×10-5exp{-(290±4)kJmol-1/RT} m2 s-1 and DAu*=1.4×10 -3exp(-310kJmol-1/RT) m2 s-1, respectively. The value of the activation energy at 5 GPa H2 is 20 kJ mol-1 larger than that at 0.1 MPa Ar, whereas the value of the pre-exponential factor at 5 GPa H2 is 17 times larger than that at 0.1 MPa Ar. Therefore, the enhancement of the diffusion at 5 GPa H2 is attributed to a high value of activation entropy.

Original languageEnglish
Pages (from-to)1247-1254
Number of pages8
JournalActa Materialia
Volume52
Issue number5
DOIs
Publication statusPublished - Mar 8 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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