The structure of the intermetallic phase FeAl<sub>6</sub>

Walford, L. K.

doi:10.1107/s0365110x65000610

Cited by 98 publications

(19 citation statements)

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“…However, due to its low solubility in Al, Fe may be present as secondary phases in the form of intermetallics. [6][7][8][9][10][11][12] Although it has been demonstrated that these particles can strengthen and increase the temperature resistance with little increase in weight, an effective use of Fe as a major alloying element in structural alloys of Al has not been possible to date. The secondary phases cannot be manipulated easily through conventional deformation and heat treatment including supersaturation and subsequent aging for fine precipitation.…”

Section: Introductionmentioning

confidence: 98%

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Cubero-Sesín

Horita

2015

Metall Mater Trans A

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A cast Al-2 wt pct Fe alloy was processed by high-pressure torsion (HPT) at room temperature and then subjected to artificial aging at temperatures of 373 K and 473 K (100°C and 200°C). The aging behavior was studied by Vickers microhardness measurements and by microstructural analyses using transmission electron microscopy and X-ray diffraction. The initial intermetallic structures, composed of a mixture of Al + Al 6 Fe and Al + Al 3 Fe eutectics phases, were partially dissolved in the matrix up to a supersaturation of~1 wt pct Fe. The microstructure was refined by HPT to an ultrafine-grained level with a minimum grain size of~120 nm in the matrix and a dispersion of particles less than 400 nm. Age hardening was achieved within 0.25 hours at 473 K (200°C), to a maximum UTS of~700 MPa as a result of nano-sized precipitation within the ultrafine grains. The uniform elongation exceeded~12 pct even at intermediate levels of imposed strain by HPT, while it decreased to~6 pct with the subsequent aging treatment. The thermal stability of the ultrafine-grained structure was verified to exceed 16 days at 373 K (100°C) and 12 hours at 473 K (200°C).

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Section: Introductionmentioning

confidence: 98%

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Cubero-Sesín

Horita

2015

Metall Mater Trans A

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“…[6] Several studies by other workers, [7,8,9] have focused upon the Al-rich part of the system, where the u-Al 3 Fe, a-AlFeSi, and b-AlFeSi phases have been reported as equilibrium phases. [9,10] In addition, some nonequilibrium phases have been identified, for example, metastable phases such as Al 6 Fe, [3,11,12] Al m Fe, [13,14] and Al x Fe [3,15] instead of the u-Al 3 Fe (or u-Al 13 Fe 4 ) [16,17] equilibrium phase. Structures of various phases, e.g., Al 6 Fe, [13,18] Al 3 Fe, [11,19] and a-AlFeSi [20,21,22] have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Iron intermetallic phases in the Al corner of the Al-Si-Fe system

Khalifa

Samuel

Gruzleski

2003

Metall Mater Trans A

154

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The iron intermetallics observed in six dilute Al-Si-Fe alloys were studied using thermal analysis, optical microscopy, and image, scanning electron microscopy/energy dispersive X-ray, and electron probe microanalysis/wavelength dispersive spectroscopy (EPMA/ WDS) analyses. The alloys were solidified in two different molds, a preheated graphite mold (600 °C) and a cylindrical metallic mold (at room temperature), to obtain slow (ϳ0.2 °C/s) and rapid (ϳ15 °C/s) cooling rates. The results show that the volume fraction of iron intermetallics obtained increases with the increase in the amount of Fe and Si added, as well as with the decrease in cooling rate. The low cooling rate produces largersized intermetallics, whereas the high cooling rate results in a higher density of intermetallics. Iron addition alone is more effective than either Si or Fe ϩ Si additions in producing intermetallics. The alloy composition and cooling rate control the stability of the intermetallic phases: binary Al-Fe phases predominate at low cooling rates and a high Fe:Si ratio; the b-Al 5 FeSi phase is dominant at a high Si content and low cooling rate; the a-iron intermetallics (e.g., a-Al 8 Fe 2 Si) exist between these two; while Si-rich ternary phases such as the d-iron Al 4 FeSi 2 intermetallic are stabilized at high cooling rates and Si contents of 0.9 wt pct and higher. Calculations of the solidification paths representing segregations of Fe and Si to the liquid using the Scheil equation did not conform to the actual solidification paths, due to the fact that solid diffusion is not taken into account in the equation. The theoretical models of Brody and Flemings [44] and Clyne and Kurz [45] also fail to explain the observed departure from the Scheil behavior, because these models give less weight to the effect of solid back-diffusion. An adjusted 500 °C metastable isothermal section of the Al-Si-Fe phase diagram has been proposed (in place of the equilibrium one), which correctly predicts the intermetallic phases that occur in this part of the system at low cooling rates (ϳ0.2 °C/s).

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“…Formation of Al 3 Fe seems to be easy in comparison with that of Al 6 Fe from the view point of orientation relationships. However, the monoclinic crystal structure of the Al 3 Fe, composed of 102 atoms in a unit cell, 12) is very complicated, whereas crystal structure of the Al 6 Fe, orthorhombic with 28 atoms in a unit cell, 13) is relatively simple. Moreover, the atomic volume of the Al 3 Fe phase is about 0.0191 nm 3 , larger than that of Al 6 Fe, about 0.0176 nm 3 .…”

Section: Precipitation Sequencementioning

confidence: 99%

“…The bright field image (c) was taken by tilting the specimen in order to show the precipitate clearly. The SADP can be indexed as the matrix and the metastable precipitate Al 6 Fe (orthorhombic, a 0 ¼ 0:6464, b 0 ¼ 0:7440, c 0 ¼ 0:8779 nm 13) ). However, it is necessary to take such diffraction pattern which composes of low index planes in order to distinguish Al 6 Fe from Al 3 Fe, because the lattice parameters in both phases are too large.…”

Section: )mentioning

confidence: 99%

Precipitation in an Al-300 ppm Fe Alloy

2004

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Precipitation in deformed and undeformed Al-300 ppm Fe alloy has been investigated by means of resistivity measurements and transmission electron microscopy. The undeformed specimens were solution-heat-treated at 913 K for 3.6 ks, quenched in iced water and then aged at the temperatures between 393 and 848 K, while the deformed specimens were cold-drawn for resistivity measurement or cold-rolled for TEM observations after the same solution heat treatment, and then aged. Resistivity in the undeformed specimens decreased in two stages, while in the deformed specimens, resistivity decreased in two or three stages depending on aging temperatures. Time-Temperature-Precipitation (TTP) diagram for the undeformed specimens consisted of one C-curve which corresponded to precipitation of stable Al 3 Fe. The TTP diagram for the 65% cold-drawn specimens was separated into two C-curves: the curves in high and low temperature ranges corresponded to precipitation of Al 3 Fe and Al 6 Fe, respectively. The precipitation of metastable Al 6 Fe was observed only in the cold-rolled specimens. Acceleration effects of cold drawing on Al 3 Fe precipitation were hardly recognized.

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The structure of the intermetallic phase FeAl₆

Abstract: The structure of FeA1 e has been refined. The unit cell is orthorhombic and the structure is isostructural with MnA16 and with a-FeCuA1, which is a copper-stabilized form of FeAle.

Cited by 98 publications

References 1 publication

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Iron intermetallic phases in the Al corner of the Al-Si-Fe system

Precipitation in an Al-300 ppm Fe Alloy

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The structure of the intermetallic phase FeAl6

Abstract: The structure of FeA1 e has been refined. The unit cell is orthorhombic and the structure is isostructural with MnA16 and with a-FeCuA1, which is a copper-stabilized form of FeAle.

Cited by 98 publications

References 1 publication

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Age Hardening in Ultrafine-Grained Al-2 Pct Fe Alloy Processed by High-Pressure Torsion

Iron intermetallic phases in the Al corner of the Al-Si-Fe system

Precipitation in an Al-300 ppm Fe Alloy

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The structure of the intermetallic phase FeAl₆