Electronic Resource
s.l. ; Stafa-Zurich, Switzerland
Solid state phenomena
Vol. 139 (Apr. 2008), p. 157-164
ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
Carbon atoms are always present in Fe-based materials, either as impurities even in highpurity samples or as an intrinsic constituent in steels. Density Functional Theory calculations havebeen performed to study the interaction between C atoms and vacancies (V) in α-Fe. We find thatthe formation of VCn complexes is energetically favourable for n ≤ 3, with VC2 being the moststable one. The energy gain corresponding to the clustering reaction VCn-1 + C → VCn dependsmainly on the strength of C-C covalent bonds. The vacancy diffusivity is shown to be significantlymodified by the formation of vacancy-carbon complexes, exhibiting non-Arrhenius behaviour.Effective vacancy diffusion coefficients in α-Fe are calculated as a function of temperature andcarbon content using a simplified thermodynamic model. The results are discussed in detail in thelimiting case of excess of C with respect to vacancies
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.139.157.pdf
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