Formation of FeNi with<i>L</i>1<sub>0</sub>-ordered structure using high-pressure torsion

Lee, Seungwon; Edalati, Kaveh; Iwaoka, Hideaki; Horita, Zenji; Ohtsuki, Takumi; Ohkochi, Takuo; Kotsugi, Masato; Kojima, Takayuki; Mizuguchi, Masaki; Takanashi, Kōki

doi:10.1080/09500839.2014.955546

Cited by 86 publications

(44 citation statements)

References 30 publications

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“…S1). While there have been reports of L1 0 superlattice peak detection in X-ray diffraction experiments for bulk FeNi processed samples [26,27], it remains an open question as to whether the detected peaks are signatures of L1 0 -type chemical order or if they correspond to other phases with Bragg reflections overlapping the L1 0 FeNi superstructure peaks of interest. For example, easily produced oxides such as Fe 2 O 3 , Fe 3 O 4 and NiFe 2 O 4 are confirmed to exhibit a highintensity Bragg reflection at a d-spacing that coincides with the (110) L1 0 FeNi superlattice peak.…”

Section: Introductionmentioning

confidence: 98%

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

et al. 2016

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a b s t r a c tSynthesis of a new tetragonal phase at the equiatomic composition in the archetypal binary Fe-Ni phase diagram is reported. This new phase is proposed as a transitional phase linking cubic FeNi with the chemically ordered tetragonal L1 0 FeNi compound, tetrataenite, of interest as a new advanced permanent magnetic material. This new tetragonal phase was created in a selection of nominally equiatomic FeNi alloys, made either from natural Fe and Ni or from natural Fe combined with the 62 Ni isotope, via application of high-strain processing methods followed by an annealing protocol. High-resolution neutron diffraction affirms that all unprocessed samples adopt the A1-type cubic structure (space group Fm3m) while all fully processed samples adopt the chemically disordered A6-type tetragonal structure (space group I4/mmm). Magnetic characterization documents a decrease in the initial magnetic susceptibility of deformed samples after annealing, evidencing a processing-induced increase in magnetic anisotropy that may be entirely accounted for by the measured tetragonal distortion. It is proposed that this new phase is a precursor to the formation of tetrataenite (L1 0 FeNi, space group P4/mmm), a meteoritic mineral of high magnetization and appreciable magnetocrystalline anisotropy that requires extraordinarily long cooling periods to form in nature. These results furnish new fundamental information as well as engineering insight for terrestrial synthesis of tetrataenite on industrial timescales, with high relevance for the creation of next-generation permanent magnets comprised entirely of easily accessible, earth-abundant elements.

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Section: Introductionmentioning

confidence: 98%

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

et al. 2016

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“…Furthermore, it is essential to derive single-phase L 1 0 -FeNi as bulk or bulkable powder. Artificially synthesized L 1 0 –FeNi bulk materials reported thus far have a low S and/or low abundance ratio 9–12 . The extremely low stability of the L 1 0 structure prevents the formation of high- S , single-phase bulk L 1 0 –FeNi.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

Goto¹,

Kura²,

Watanabe³

et al. 2017

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102

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Tetrataenite (L10-FeNi) is a promising candidate for use as a permanent magnet free of rare-earth elements because of its favorable properties. In this study, single-phase L10-FeNi powder with a high degree of order was synthesized through a new method, nitrogen insertion and topotactic extraction (NITE). In the method, FeNiN, which has the same ordered arrangement as L10-FeNi, is formed by nitriding A1-FeNi powder with ammonia gas. Subsequently, FeNiN is denitrided by topotactic reaction to derive single-phase L10-FeNi with an order parameter of 0.71. The transformation of disordered-phase FeNi into the L10 phase increased the coercive force from 14.5 kA/m to 142 kA/m. The proposed method not only significantly accelerates the development of magnets using L10-FeNi but also offers a new synthesis route to obtain ordered alloys in non-equilibrium states.

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“…The FeNi L1 0 structure is a stable phase [9,10] but it is rare in nature, only occurring in meteorites, and it is difficult to synthesize due to the low temperature phase boundary. It has been studied in meteoritic samples [10,11,12] and has been synthesized through neutron bombardment (Néel [13] and Pauleve [14]), electron irradiation (Chamberod [15] and Reuter [16]), in thin film form (Kojima and Mizuguchi [8]), through severe plastic deformation (Lee [17]) and recently through a chemical process (Makino [18]). In all of these methods only very small amounts of the phase are produced.…”

Section: Introductionmentioning

confidence: 99%

Resonant x-ray diffraction revealing chemical disorder in sputtered L1₀FeNi on Si(0 0 1)

Frisk

Lindgren

Pappas

et al. 2016

J. Phys.: Condens. Matter

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Resonant x-ray diffraction revealing chemical disorder in sputtered L10 FeNi on Si(0 0 1). Physics: Condensed Matter, 28(40) Abstract. In the search for new rare earth free permanent magnetic materials, FeNi with the L1 0 structure is a possible candidate. We have synthesized the phase in thin film form by sputtering onto HF-etched Si(001) substrates. Monatomic layers of Fe and Ni were alternately deposited on a Cu buffer layer, all of which grew epitaxially on the Si substrates. A good crystal structure and epitaxial relationship was confirmed by in-house X-ray diffraction (XRD). The chemical order, which to some part is the origin of an uniaxial magnetic anisotropy, was measured by resonant XRD. The 001 superlattice reflection was split in two symmetrically spaced peaks due to a composition modulation of the Fe and Ni layers. Furthermore the influence of roughness induced chemical anti-phase domains on the RXRD pattern is exemplified. A smaller than expected magnetic uniaxial anisotropy energy was obtained, which is partly due to the composition modulations, but the major reason is concluded to be the Cu buffer surface roughness. Journal of

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Formation of FeNi withL1₀-ordered structure using high-pressure torsion

Cited by 86 publications

References 30 publications

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

Resonant x-ray diffraction revealing chemical disorder in sputtered L1₀FeNi on Si(0 0 1)

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Formation of FeNi withL10-ordered structure using high-pressure torsion

Cited by 86 publications

References 30 publications

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi

Synthesis of single-phase L10-FeNi magnet powder by nitrogen insertion and topotactic extraction

Resonant x-ray diffraction revealing chemical disorder in sputtered L10FeNi on Si(0 0 1)

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Formation of FeNi withL1₀-ordered structure using high-pressure torsion

Resonant x-ray diffraction revealing chemical disorder in sputtered L1₀FeNi on Si(0 0 1)