Stability and structures of the CFCC-TmC phases: a first-principles study

Fang, C.; van Huis, Marijn A.; Zandbergen, H.

Stability and structures of the CFCC-TmC phases: a first-principles study

Journal article (2012)

Authors

C. Fang

Marijn A. van Huis

H. Zandbergen

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Published Date

2012

Language

English

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Abstract

The eta-1-M(6)C, gamma-M(23)C(6), and pi-M(11)C(2) phases (M = Cr, Mn and Fe) have complex cubic lattices with lattice parameters of approximately 1.0 nm. They belong to the CFCC-TmC family (complex face-centered cubic transition metal carbides), display a rich variety of crystal structures, and play in important role in iron alloys and steels. Here we show that first-principles calculations predict high stability for the gamma-M(23)C(6) and eta-M(6)C phases, and instability for the pi-M(11)C(2) phases, taking into account various compositional and structural possibilities. The calculations also show a wide variety in magnetic properties. The Cr-containing phases were found to be non-magnetic and the Fe-phases to be ferromagnetic, while the Mn-containing phases were found to be either ferrimagnetic or non-magnetic. Details of the local atomic structures, and the formation and stability of these precipitates in alloys are discussed.