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Updated: Oct 3, 2025
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Oscillatory Mechanism of α-Fe(N) ↔ γ'-Fe4N Phase Transformations during Nanocrystalline Iron Nitriding
Walerian Arabczyk1, Katarzyna Skulmowska1, Rafał Pelka1
1Department of Inorganic Chemical Technology and Environment Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology in Szczecin, Piastów Ave. 42, 71-065 Szczecin, Poland.
Abstract:
The kinetics of nanocrystalline α-iron nitriding to γ'-iron nitride in an ammonia atmosphere was studied at 598-648 K and at atmospheric pressure. Oscillatory changes in nitriding reaction rates depending on nitrogen concentration in a solid sample were observed. This phenomenon was explained by a gradual change in the iron active surface coverage degree, with nitrogen resulting from a gradual change in the free enthalpy of nitrogen segregation. The α-Fe(N) nanocrystallites' transformation into γ'-Fe4N went through six metastable FeNx states. The continuous function proposed by Fowler and Guggenheim was modified to a stepwise variable function.
