Synthesis of fine α″-Fe16N2 powders by low-temperature nitridation of α-Fe from magnetite nanoparticles

Li, Jing; Yuan, Wei; Peng, Xiaoling; Yang, Yanting; Xu, Jingcai; Wang, Xinqing; Hong, Bo; Jin, Hongxiao; Jin, Dingfeng; Ge, Hongliang

doi:10.1063/1.4967950

Cited by 11 publications

(8 citation statements)

References 15 publications

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“…Among dozens of articles, only a few works claimed pure α″Fe 16 N 2 phase preparation. commonly, the prepared Fe-N samples consist of several possible phases with a partial volume ratio of an α″Fe 16 N 2 phase inside, but just a volume fraction of this phase defines magnetic proper ties: the higher volume fraction, the better properties [22,84,85]. In this respect, a key parameter to evaluate the quality of the prepared compound and its magnetic properties is information on the volume ratio of α″Fe 16 N 2 phase.…”

Section: Fabrication Methods and Structurementioning

confidence: 99%

Martensitic αʺ-Fe16N2-Type Phase of Non-Stoichiometric Composition: Current Status of Research and Microscopic Statistical-Thermodynamic Model

Radchenko¹,

Gatsenko²,

Lizunov³

et al. 2020

Usp. Fiz. Met.

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The literature (experimental and theoretical) data on the tetragonality of martensite with interstitial–substitutional alloying elements and vacancies are reviewed and analysed. Special attention is paid to the studying the martensitic αʺ-Fe16N2-type phase with unique and promising magnetic properties as an alternative to the rare-earth intermetallics or permendur on the world market of the production of permanent magnets. The period since its discovery to the current status of research is covered. A statistical-thermodynamic model of ‘hybrid’ interstitial–substitutional solid solution based on a b.c.t. crystal lattice, where the alloying non-metal constituents (impurity atoms) can occupy both interstices and vacant sites of the host b.c.c.(t.)-lattice, is elaborated. The discrete (atomic-crystalline) lattice structure, the anisotropy of elasticity, and the ‘blocking’ and strain-induced (including ‘size’) effects in the interatomic interactions are taken into account. The model is adapted for the non-stoichiometric phase of Fe–N martensite maximally ordered by analogy with αʺ-Fe16N2, where nitrogen atoms are in the interstices and at the sites of b.c.t. iron above the Curie point. It is stressed an importance of adequate data on the available (in the literature) temperature- and concentration-dependent microscopic energy parameters of the interactions of atoms and vacancies. The features of varying (viz. non-monotonic decreasing with increasing temperature) the relative concentration of N atoms in the octahedral interstices of b.c.t. Fe, and therefore, the degree of its tetragonality (correlating with this concentration) are elucidated. Within the wide range of varying the total content of introduced N atoms, the ratio of the equilibrium concentration of residual site vacancies to the concentration of thermally activated vacancies in a pure b.c.c. Fe is demonstrated at a fixed temperature.

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Section: Fabrication Methods and Structurementioning

confidence: 99%

Martensitic αʺ-Fe16N2-Type Phase of Non-Stoichiometric Composition: Current Status of Research and Microscopic Statistical-Thermodynamic Model

Radchenko¹,

Gatsenko²,

Lizunov³

et al. 2020

Usp. Fiz. Met.

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“…In practice, high value of forward pressure results in severe plastic deformation of powder par ticles, suggesting flattening and mechanical interlocking the splats by cold forging. however, adiabatic shear instability under high strain rate resulted from high impact velocity is primary responsible for effec tive metallic bonding between the adjacent particles [81][82][83][84][85][86]. high value of forward pressure and very short contact time of impact about 10 8 s [85,86], favours particle surface softening and shear localisation.…”

Section: Structural Characterization Of Bulk-shaped Quasi-crystalline...mentioning

confidence: 99%

“…however, adiabatic shear instability under high strain rate resulted from high impact velocity is primary responsible for effec tive metallic bonding between the adjacent particles [81][82][83][84][85][86]. high value of forward pressure and very short contact time of impact about 10 8 s [85,86], favours particle surface softening and shear localisation. this bonding process is commonly considered as that comparable with explo sive welding or shock wave powder compaction [87].…”

Section: Structural Characterization Of Bulk-shaped Quasi-crystalline...mentioning

confidence: 99%

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confidence: 99%

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2020

Usp. Fiz. Met.

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“…After the first report by Kim and Takahashi on the giant saturation magnetization of about 290 emu/g of the α -Fe 16 N 2 phase in the evaporated Fe-N thin film, many researchers have made sustained efforts on both the fundamental [8,9] and practical aspects of preparing of the α -Fe 16 N 2 material. Thus, several attempts have been successfully made to develop magnetic materials containing α -Fe 16 N 2 phase in the form of thin films [10][11][12][13], foils [14,15], rods [16], ribbons [17], nanocones [18], and nanoparticles and powders [19,20], by using different preparation methods. The reported values of saturation magnetizations were widely scattered from 230 to 315 emu/g and appeared to be inconsistent and sometimes contradictory.…”

Section: Introductionmentioning

confidence: 99%

Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

Grigoras,

Lostun,

Porcescu

et al. 2023

Crystals

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The iron nitride materials, especially α″-Fe16N2, are considered one of the most promising candidates for future rare-earth-free magnets. However, the mass production of α″-Fe16N2 powders as a raw material for permanent magnets is still challenging. In this work, starting from iron lumps as a raw material, we have managed to prepare the α″-Fe16N2 powders via the gas atomization method, followed by subsequent nitriding in an ammonia–hydrogen gas mixture stream. The particle size was controlled by changing the gas atomization preparation conditions. X-ray diffractograms (XRD) analyses show that the prepared powders are composed of α″-Fe16N2 and α-Fe phases. The α″-Fe16N2 volume ratio increases with decreasing powder size and increasing nitriding time, reaching a maximum of 57% α″-Fe16N2 phase in powders with size below 32 ± 3 μm after 96 h nitridation. The saturation magnetization reaches the value of 237 emu/g and a reasonable coercivity value of 884 Oe. Compared to the saturation magnetization values of α-Fe powders, the α″-Fe16N2 powders prepared through our proposed approach show an increase of up to 10% in saturation and demonstrate the possibility of mass production of α″-Fe16N2 powders as precursors of permanent magnets without rare earths.

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Synthesis of fine α″-Fe16N2 powders by low-temperature nitridation of α-Fe from magnetite nanoparticles

Cited by 11 publications

References 15 publications

Martensitic αʺ-Fe16N2-Type Phase of Non-Stoichiometric Composition: Current Status of Research and Microscopic Statistical-Thermodynamic Model

Martensitic αʺ-Fe16N2-Type Phase of Non-Stoichiometric Composition: Current Status of Research and Microscopic Statistical-Thermodynamic Model

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Innovative Method for the Mass Preparation of α″-Fe16N2 Powders via Gas Atomization

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