Oscillatory Mechanism of α-Fe(N) ↔ γ’-Fe(4)N Phase Transformations during Nanocrystalline Iron Nitriding

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 g...

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Detalles Bibliográficos
Autores principales: Arabczyk, Walerian, Skulmowska, Katarzyna, Pelka, Rafał, Lendzion-Bieluń, Zofia
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Communication
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8838475/
https://www.ncbi.nlm.nih.gov/pubmed/35160951
http://dx.doi.org/10.3390/ma15031006
Descripción
Sumario: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’-Fe(4)N went through six metastable FeN(x) states. The continuous function proposed by Fowler and Guggenheim was modified to a stepwise variable function.

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