Self-diffusion in b.c.c. and ordered phases of an equiatomic iron-cobalt alloy
- Tohoku Univ., Sendai (Japan). Dept. of Materials Science
- Chang-won National Univ. (Korea, Republic of). Dept. of Materials Science and Engineering
Self-diffusion coefficients of {sup 59}Fe and {sup 57}Co in an Fe-50.8 at.% Co alloy have been determined in the temperature range between 877 and 1,238 K by use of the sputter-microsectioning technique. Above the order-disorder transformation temperature (1,003 K), the Arrhenius plots of the self-diffusion coefficients of both components show a slight deviation from linearity due to the magnetic spin ordering of the alloy. Below 1,003 K the Arrhenius plots become curved downward remarkably owing to the B2 type of atomic ordering. The temperature dependence of the self-diffusion coefficients D{sub Fe} and D{sub Co} across the phase transformation temperature can be expressed by D{sub Fe} = 7.0 {times} 10{sup {minus}4}exp{l_brace}{minus}(241 kJ mol{sup {minus}1})[1 + 0.16s{sup 2} + 0.21u{sup 2}]/RT{r_brace}m{sup 2}s{sup {minus}1} and D{sub Co} = 0.31 {times} 10{sup {minus}4}exp{l_brace}{minus}(201 kJ mol{sup {minus}1})[1 + 0.29s{sup 2} + 0.27u{sup 2}]/RT{r_brace}m{sup 2}s{sup {minus}1} where s is the ratio of the spontaneous magnetization at T to that at 0 K, and u is the long range order parameter. Both the magnetic spin ordering and the atomic ordering of the alloy yield an increase in the activation energies for self-diffusion.
- OSTI ID:
- 31735
- Journal Information:
- Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 3 Vol. 43; ISSN 0956-7151; ISSN AMATEB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Volume diffusion of iron in Fe{sub 3}Al: Influence of ordering
Annealing and aging of interstitial C in {alpha}-Fe, as measured by internal friction