Studies on the formation of FeSi2 from the FeSiFe2Si5 eutectic

Sakata, T.; Sakai, Y; Yoshino, Hiroko; Fujii, Hidenobu; Nishida, Isao

doi:10.1016/0022-5088(78)90225-4

Cited by 46 publications

(15 citation statements)

References 10 publications

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“…3. This temperature is believed to indicate the peritectoid transformation (α-Fe 2 Si 5 +ε-FeSiβ-FeSi 2 ) temperature [15], which is the so-called "high temperature transformation temperature" (995 o C) [16][17][18]. However, on cooling, the peak is no longer observed but an exothermic peak appears at 858 o C instead.…”

Section: Resultsmentioning

confidence: 97%

“…However, on cooling, the peak is no longer observed but an exothermic peak appears at 858 o C instead. This is believed to indicate the "low temperature transformation temperature" (865 o C), below which the primary transformation of "α-Fe 2 Si 5 +ε-FeSiβ-FeSi 2 " and the secondary transformation of "Si+ε-FeSiβ-FeSi 2 " take place in the iron silicides [16][17][18].…”

Section: Resultsmentioning

confidence: 99%

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Properties of Co-doped N-type FeSi2 processed by mechanical alloying

Kim

Lee

2002

Met. Mater. Int.

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Iron-silicide was produced with a mechanical alloying process and consolidated through vacuum hot pressing. The as-milled powders were of metastable state and fully transformed into the β-FeSi 2 phase through subsequent isothermal annealing. The as-consolidated iron silicides consisted of an untransformed mixture of α-Fe 2 Si 5 and ε-FeSi phases and a partially transformed β-FeSi 2 phase was found in the low density compact. Isothermal annealing was carried out to induce transformation into a thermoelectric semiconducting β-FeSi 2 phase. The transformation behavior of the β-FeSi 2 was investigated utilizing DTA, SEM, and XRD analyses. Isothermal annealing at 830 o C in vacuum led to a thermoelectric semiconducting β-FeSi 2 phase transformation, but some residual metallic α and ε phases were unavoidable even after 96 hours of annealing. The iron silicide microstructures were investigated using SEM and TEM. The mechanical and thermoelectric properties of the β-FeSi 2 materials before and after isothermal annealing are characterized in this study.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Properties of Co-doped N-type FeSi2 processed by mechanical alloying

Kim

Lee

2002

Met. Mater. Int.

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“…1b), which can be explained based on the peritectoid reaction (e + a fi b) that occurs at 982°C. 1 The eutectoid reaction, which is the decomposition of the a-phase to yield the b-phase and Si, appeared to have started, especially adjacent to the outer edge of the b-phase. EDS gave the composition of the a-phase (denoted by a in Fig.…”

Section: Resultsmentioning

confidence: 98%

Distribution of Elements in a Cu-Added FeSi2 Alloy Under Peritectoid and Eutectoid Reactions

Kiatgamolchai

Sakulkalavek

2011

Journal of Elec Materi

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The distribution of Si, Fe, and Cu in FeSi 2 alloys, with or without the addition of Cu, were studied by electron probe microanalysis (EPMA). Alloys were prepared by slow solidification from the melt. Without Cu addition, both e-and a-phases were clearly observed, and a b-phase surrounding the e-phase was additionally observed after in situ annealing at 950°C for 12 h. With inclusion of 0.5 at.% Cu, the eutectoid reaction (a fi b + Si) was enhanced greatly. Only 0.01 at.% Cu was dissolved into the e-phase, with the excess Cu atoms being largely found at the outer edge of the e-phase. Ex situ annealing at 950°C for 12 h greatly changed the distribution of Si, Fe, and Cu. The e-phase changed its Si/Fe atomic ratio from 1.470 to 1.907, indicating an early stage of the peritectoid reaction (e + a fi b) and/or the subsequent reaction (e + Si fi b), with an increase in the Cu content up to 0.04 at.%. The size of this new phase was smaller than the original e-phase, and this new phase was surrounded by a shell of Si/Fe with an atomic ratio of 0.727 to 1.788 and a Cu content of 0.01 at.% to 0.11 at.%. In situ annealing under the same condition yielded different results: a large amount of Si segregates from the a-phase matrix, leaving a Si/Fe atomic ratio of only 0.506 to 0.530. The peritectoid reaction of the e-phase was found to depend on the Cu content. For the e-phase with undetectable levels of Cu, the Si/Fe atomic ratio remained at 0.954 to 0.998, but this ratio decreased with increasing Cu content to 0.55 at 2.20 at.% Cu. A plot of at.% Cu versus Si/Fe atomic ratio revealed a local minimum at the e-phase and expectedly at both the b-and a-phases. Nonstoichiometric structures (neither a-, b-nor e-phases) seemed to have higher at.% Cu compared with those with the closest Si/Fe composition.

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“…β-FeSi2 is known as a typical thermoelectric material with large thermoelectric power and low electric resistivity [1][2][3][4]. β-FeSi2 offers additional advantages such as oxidation resistance at high temperature, and the abundance of its raw materials in natural resources has led to its being referred to as an "environmentally friendly" semiconductor.…”

Section: Introductionmentioning

confidence: 99%

Eco-Fabrication Process and Thermoelectric Properties of β-FeSi<sub>2</sub>

Shibuya

Kawata

Shinohara

et al. 2015

Trans. Mat. Res. Soc. Japan

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The thermoelectric material β-FeSi 2 was produced by a rapid eco-process involving induction-field-activated combustion synthesis / static pseudo-isostatic compaction (IFACS /SPIC). A dense Fe-Si alloy (Fe/Si = 3/7) was synthesized by IFACS/SPIC using a powder compact of high purity Fe and Si. An induction time (5 min) of IFACS/SPIC and the annealing time (at 1123 K for 5 min) for β-transformation were extremely shorter than those of conventional synthesis. When the Fe/Si ratio of the alloy used in the eutectoid reaction α-FeSi2β-FeSi2+Si was 3/7, the main annealing product was β-FeSi 2 with a small amount of free Si, and the formation of metallic ε-FeSi was prevented. The relative density and the β-transformation ratio were 95% and 96%, respectively. The thermoelectric properties of the p-type Mn-doped (Fe 2.94 Mn 0.06 Si 7 ) and the n-type Co-doped (Fe 2.94 Co 0.06 Si 7 ) products were investigated from room temperature to 1123 K.

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Studies on the formation of FeSi2 from the FeSiFe2Si5 eutectic

Cited by 46 publications

References 10 publications

Properties of Co-doped N-type FeSi2 processed by mechanical alloying

Properties of Co-doped N-type FeSi2 processed by mechanical alloying

Distribution of Elements in a Cu-Added FeSi2 Alloy Under Peritectoid and Eutectoid Reactions

Eco-Fabrication Process and Thermoelectric Properties of β-FeSi<sub>2</sub>

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