The Fe-A1-Ti system

Palm, Martin; Inden, Gerhard; Thomas, Noah

doi:10.1007/bf02667305

Cited by 111 publications

(83 citation statements)

References 14 publications

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“…Compositions of phases in the TiFe 2 Al alloy after ND and after annealing at various temperatures between 800 and 1200°C have been measured on a Cameca SX 50 and a Jeol JXA-8100 at 15 kV and 20 nA using the pure elements as standards. [44,45] For 1000°C a similar phase constitution was found by Fu et al [41] in this alloy series. Lattice parameters a as a function of Ni content (x) are plotted in Fig.…”

Section: Methodssupporting

confidence: 84%

The Heusler Phase Ti25(Fe50 − x Ni x )Al25 (0 ≤ x ≤ 50); Structure and Constitution

Yan

Grytsiv

Rogl

et al. 2008

J Phs Eqil and Diff

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Alloys with composition Ti 25 (Fe 50 2 x Ni x )Al 25 (0 £ x £ 50) were investigated employing electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD). For TiFe 2 Al, in situ neutron powder diffraction (ND) was used for the inspection of phase constitution covering the temperature range from 27°C (300 K) to 1277°C (1550 K). Combined Rietveld refinement of ND and XPD data for TiFe 2 Al revealed that Fe atoms occupy the 8c site in space group Fm " 3m; Ti with a small amount of Al sharing the 4a site, and the remaining Ti and Al atoms adopting the 4b site. This structural model was successfully applied in the refinement of all alloys Ti 25 (Fe 50 2 x Ni x )Al 25 (0 £ x £ 50). Partial atom order exists on the Fe-rich side while complete order is observed for the Ni-rich side. Profiles recorded by in situ neutron powder diffraction for TiFe 2 Al in the range of investigated temperatures show two phases, namely Heusler phase and MgZn 2 -type Laves phase. Diffraction peaks from the Heusler phase dominate the profiles at lower temperatures but at higher temperatures the MgZn 2 -type Laves phase is the main phase. No CsCl-type phase was found in the alloy in the investigated temperature range. The thermal expansion coefficient of TiFe 2 Al is 1.4552310 25 K 21 .

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Section: Methodssupporting

confidence: 84%

The Heusler Phase Ti25(Fe50 − x Ni x )Al25 (0 ≤ x ≤ 50); Structure and Constitution

Yan

Grytsiv

Rogl

et al. 2008

J Phs Eqil and Diff

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“…Some possible explanations for the observed irregularities including other long-range ordered states, short-range ordering, two-phase structure, material impurities such as carbide precipitation and quenched-in vacancies are proposed [35,[37][38][39]. The different phases and their lattice structure and lattice parameters are listed in Table 1 [9,[40][41][42][43][44][45][46]. Figure 4 [47] shows the extension of the solid solution of Al in Fe from 0 up to 45 at.…”

Section: Phase Diagrammentioning

confidence: 99%

A Review on the Properties of Iron Aluminide Intermetallics

2016

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Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i) alloy composition; (ii) microstructure; and (iii) number (type) of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro-and nano-mechanical testing methods in addition to the fabrication techniques of micro-and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above.

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“…Almost 33.5 at.% Fe can be replaced by Al at 800°C, and a value of 47 at.% can be reached at 1000°C. [28] In a previous work, we showed that Al substitution takes place on two crystallographically different Fe positions simultaneously. [26] Determination of phase relations in the system Ti-Ni-Al [30][31][32] revealed a large homogeneity region for the ternary Laves phase with MgZn 2 -type structure: Ti(Ti y Ni x Al 1-x-y ) 2 .…”

Section: Introductionmentioning

confidence: 99%

“…[36] It is interesting to note that for the G phase in the ternary Ti-Fe-Al system, two-phase fields exist corresponding to the Ti-rich side and Al-rich side, respectively. [9,28] Our previous work defined the structure varieties, [35,37,38] that is, the loss of symmetry in the G phase as a function of composition resulting in a space group change from Fm " 3m (Al-rich) to F " 43m (Al-poor). [35] In a previous investigation on a series of alloys Ti(Fe 50-x Ni x )Al, we elucidated atom site preferences for the Heusler phase in the quaternary system.…”

Section: Introductionmentioning

confidence: 99%

“…[20] In this work, we evaluate the homogeneity regions of the quaternary Laves phase with MgZn 2 -type structure in continuation of our investigation on the ternary Laves phases Ti-Fe-Al [25] and Ti-Ni-Al. [26] Several researchers [4,9,[27][28][29] have dealt with the phase diagram Ti-Fe-Al, in which a large solid solubility of Al in the binary Laves phase TiFe 2 exists. Almost 33.5 at.% Fe can be replaced by Al at 800°C, and a value of 47 at.% can be reached at 1000°C.…”

Section: Introductionmentioning

confidence: 99%

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On the Quaternary System Ti-Fe-Ni-Al

Yan

Grytsiv

Rogl

et al. 2008

J Phs Eqil and Diff

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The homogeneity ranges of the Laves phases and phase relations concerning the Laves phases in the quaternary system Ti-Fe-Ni-Al at 900°C were defined by x-ray powder diffraction (XPD) data and electron probe microanalysis (EPMA). Although at higher temperatures the Laves phase forms a continuous solid solution, two separate homogeneity fields of TiFe 2 -based (denoted by k Fe ) and Ti(TiNiAl) 2 -based (denoted by k Ni ) Laves phases appear at 900°C. The relative locations of Laves phases, G phase, Heusler phase, and CsCl-type phase as well as the associated tie-tetrahedra were experimentally established in the quaternary for 900°C and presented in three-dimensional (3D) view. Furthermore, a partial isothermal section TiFe 2 -TiAl 2 -TiNi 2 was constructed, and a connectivity scheme, derived for equilibria involving Laves phases in the Ti-Fe-Ni-Al quaternary system at 900°C was derived. As a characteristic feature of the quaternary phase diagram, the solid solubility of fourth elements in both the TiFe 2 -based and Ti(NiAl) 2 -based Laves phases is limited at 900°C and is dependent on the ternary Laves phase composition. A maximum solubility of about 8 at.% Ni is reached for composition Ti 33.3 Fe 33.3 Al 33.4 . Structural details have been evaluated from powder x-ray and neutron diffraction data for (i) the Ti-Fe-Ni ternary and the Ti-Fe-Ni-Al quaternary Laves phases (MgZn 2 -type, space group: P6 3 /mmc) and (ii) the quaternary G phase. Atom site occupation behavior for all phases from the quaternary system corresponds to that of the ternary systems. For the quaternary Laves phase, Ti occupies the 4f site and additional Ti (for compositions higher than 33.3 at.%Ti) preferably enters the 6h site. Aluminum and (Fe,Ni) share the 6h and the 2a sites. The compositional dependence of unit cell dimensions, atomic coordinates, and interatomic distances for the Laves phases from the quaternary system is discussed. For the quaternary cubic G phase, a centrosymmetric as well as a noncentrosymmetric variety was observed depending on the composition: from combined x-ray and neutron powder diffraction measurements Ti 33.33 Fe 13.33 Ni 10.67 Al 42.67 was found to adopt the lower symmetry with space groupF " 43m.

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The Fe-A1-Ti system

Cited by 111 publications

References 14 publications

The Heusler Phase Ti25(Fe50 − x Ni x )Al25 (0 ≤ x ≤ 50); Structure and Constitution

The Heusler Phase Ti25(Fe50 − x Ni x )Al25 (0 ≤ x ≤ 50); Structure and Constitution

A Review on the Properties of Iron Aluminide Intermetallics

On the Quaternary System Ti-Fe-Ni-Al

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