The origin of predominance of cementite among iron carbides in steel at elevated temperature

Conference paper (2011)

Authors

M.H.F. Sluiter OLD Virtual Materials and Mechanics
C.K. Ande OLD Virtual Materials and Mechanics
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Published Date

2011

Language

English

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Abstract

A systematic first-principles study was conducted on the stability of binary iron carbides. The calculations showed that all the binary iron carbides are unstable relative to the elemental solids (¿-Fe and graphite). Apart from a cubic Fe23C6 phase, the energetically most favorable carbides exhibit hexagonal close-packed (hcp) Fesublattices. Structural relaxation of the hcp iron carbides was analyzed and discussed together with their relative thermodynamically stability. Finite-temperature analysis showed that contributions from lattice vibration and anomalous magnetic ordering (Curie-Weiss behavior), rather than from the conventional lattice mismatch with the matrix, are the origin of the high stability and predominance of cementite among the iron carbides in steels.