TY - JOUR
T1 - Enhanced diffusion of Au in γ-Fe by vacancies induced under elevated hydrogen pressure
AU - Yamazaki, Yoshihiro
AU - Iijima, Yoshiaki
AU - Okada, Masuo
N1 - Funding Information:
The present work was supported in part by a Grant-in-Aid for Encouragement of Young Scientists, Nos. 13750606 and 15760486 from the Ministry of Education, Science, Sports and Culture and by the grant from the Iketani Science and Technology Foundation.
PY - 2004/3/8
Y1 - 2004/3/8
N2 - 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.
AB - 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.
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U2 - 10.1016/j.actamat.2003.11.008
DO - 10.1016/j.actamat.2003.11.008
M3 - Article
AN - SCOPUS:1242265442
SN - 1359-6454
VL - 52
SP - 1247
EP - 1254
JO - Acta Materialia
JF - Acta Materialia
IS - 5
ER -