Thermodynamics and long-range order of interstitials in an h.c.p. lattice: Nitrogen in {var_epsilon}-Fe{sub 2}N{sub 1{minus}z}

Journal Article · Thu May 01 04:00:00 EDT 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(96)00307-2· OSTI ID:509139

Somers, M A.J.; Kooi, B J; Mittemeijer, E J; Horst, A.A. van der; Kraan, A.M. van der; Pers, N.M. van der ^[1]; Maldzinski, L ^[2]

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1. Delft Univ. of Technology (Netherlands)
2. Poznan Univ. of Technology (Poland). Inst. Technologii Budowy Maszyn

The thermodynamics of nitrogen in the {var_epsilon}-Fe{sub 2}N{sub 1{minus}z} phase were evaluated. To this end absorption isotherms for nitrogen in {var_epsilon}-Fe{sub 2}N{sub 1{minus}z}, depicting the dependence of the nitrogen content on the applied chemical potential of nitrogen, were determined in the temperature range 673--823 K by equilibrating iron foils in gaseous ammonia/hydrogen mixtures. The absorption isotherms could be described very well by a Gorsky-Bragg-Williams approximation for long-range order (LRO) of nitrogen atoms on the hexagonal nitrogen sublattice, formed by the octahedral interstices of the h.c.p. sublattice of iron atoms. The actual occurrence of LRO was evidenced by diffraction analysis. Moessbauer spectra were interpreted as composed of spectra of iron atoms surrounded by 1--3 nitrogen atoms. The relative amounts of the iron environments as determined from the Moessbauer spectra agreed very well with the corresponding probabilities predicted by the LRO model.

• OSTI ID: 509139
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
AMMONIA
CRYSTAL MODELS
CRYSTAL STRUCTURE
HCP LATTICES
HYDROGEN
INTERSTITIALS
IRON NITRIDES
NITROGEN
ORDER PARAMETERS
THERMODYNAMICS