Modeling thermodynamics of Fe-N phases: characterisation of epsilon-Fesub2Nsub1-x

Marjon I. Pekelharing, Amarante Böttger, Marcel A. J. Somers, Michel P. Steenvoorden, Adrie M. van der Kraan, Eric J. Mittemeijer

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    Abstract

    In the present work homogeneous epsilon-nitride powders prepared at 723 K, having nitrogen contents ranging from 26.1 at. % N (z=0.29) to 31.1 at.% N (z=0.10), were investigated with X-ray diffraction (XRD) and Mössbauer spectroscopy. A thermodynamic model accounting for the two possible configurations of LRO of the N atoms was fitted to the N-absorption isotherm at 723 K and resulted in the occupancies of the sites of the nitrogen sublattice. A miscibility gap between configurations A and B was predicted. The XRD results did not allow for an unambiguous identification of configuration A, because the discriminating superstructure reflections (with respect to h.c.p. Fe) associated with configuration A were not observed. On the other hand, the probabilities of Fe atoms surrounded by 1 up to 3 N atoms, as derived from the Mössbauer spectra, are consistent with the distribution of nitrogen over the available sites and the occurrence of a two phase region A+B as predicted by the model. The discrepancy between XRD and Mössbauer results is discussed in terms of a reason for extinguished superstructure reflections in the X-ray diffractogram of configuration A.
    Original languageEnglish
    Title of host publicationMaterials Science Forum, vols. 318-320
    Place of PublicationSwitzerland
    PublisherTrans Tech Publications
    Publication date1999
    Pages115-120
    Publication statusPublished - 1999
    EventHigh Nitrogen Steels 98 - Stockholm-Helsinki
    Duration: 1 Jan 1998 → …

    Conference

    ConferenceHigh Nitrogen Steels 98
    CityStockholm-Helsinki
    Period01/01/1998 → …

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