The Al-Rich Part of the Fe-Al Phase Diagram

Li, Xin; Scherf, Anke; Heilmaier, Martin; Stein, Frank

doi:10.1007/s11669-015-0446-7

Cited by 213 publications

(83 citation statements)

References 25 publications

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“…Density functional theory-chemical pressure (DFT-CP) analysis was carried out on all of the unique structures (Models 1-3 and 5). The stoichiometries for all models lie within the experimental phase width of the phase, where the electron concentration ranges from 15.0 to 16.1 electrons/Fe (Li et al, 2016).…”

Section: Ordered Structure Modelssupporting

confidence: 55%

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅

2019

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Many complex intermetallic structures feature a curious juxtaposition of domains with strict 3D periodicity and regions of much weaker order or incommensurability. This article explores the basic principles leading to such arrangements through an investigation of the weakly ordered channels of Fe2Al5. It starts by experimentally confirming the earlier crystallographic model of the high-temperature form, in which nearly continuous columns of electron density corresponding to disordered Al atoms emerge. Then electronic structure calculations on ordered models are used to determine the factors leading to the formation of these columns. These calculations reveal electronic pseudogaps near 16 electrons/Fe atom, an electron concentration close to the Al-rich side of the phase's homogeneity range. Through a reversed approximation Molecular Orbital (raMO) analysis, these pseudogaps are correlated with the filling of 18-electron configurations on the Fe atoms with the support of isolobal σ Fe–Fe bonds. The resulting preference for 16 electrons/Fe requires a fractional number of Al atoms in the Fe2Al5 unit cell. Density functional theory–chemical pressure (DFT-CP) analysis is then applied to investigate how this nonstoichiometry is accommodated. The CP schemes reveal strong quadrupolar distributions on the Al atoms of the channels, suggestive of soft atomic motions along the undulating electron density observed in the Fourier map that allow the Al positions to shift easily in response to compositional changes. Such a combination of preferred electron counts tied to stoichiometry and continuous paths of CP quadrupoles could provide predictive indicators for the emergence of channels of disordered or incommensurately spaced atoms in intermetallic structures.

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Section: Ordered Structure Modelssupporting

confidence: 55%

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅

2019

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“…On the other hand, this effect is balanced by the melting tendency of aluminum-rich intermetallic compounds, which are generated by the interaction of aluminum with the investigated alloy. This second feature is described by phase diagrams (Figure 13) for systems similar to the tested alloy and the limiting melting temperature for aluminum-rich intermetallic can be identified at 1160 • C [37][38][39][41][42][43]. At 1100 • C working temperature, the contact angle tests display a strong interaction between the liquid aluminum and the super duplex stainless steel substrate, involving a chemical contribution [31,44].…”

Section: Discussionmentioning

confidence: 92%

“…Since they are not stoichiometric (the alloying metallic atoms could be Me = Fe, Cr, etc. ), the intermetallic phase may be identified by aluminum atomic percentage [37][38][39]. Finally, a SEM/EBSD map has been collected at the surficial aluminum-rich layers of the super duplex stainless steel substrates of the sample annealed at 1080 • C for 360 s/mm and aluminized at 1100 • C for 2700 s, to identify and quantify through diffraction the constituent phases.…”

Section: Resultsmentioning

confidence: 99%

Hot-Dip Aluminizing on AISI F55–UNS S32760 Super Duplex Stainless Steel Properties: Effect of Thermal Treatments

Ciuffini

Barella

Cecca

et al. 2017

Metals

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Abstract:The behavior of super duplex stainless steels AISI F55-UNS S32760 in hot-dip aluminizing process has been studied, investigating the influence of cold working and of different initial microstructures obtained through a preliminary thermal treatment. The microstructural features examined are the secondary austenite precipitation, the static recovery of ferrite and the thermal dissolution of austenite within ferritic matrix. The hot-dip aluminizing temperature has been optimized through sessile drop tests. The treatment has been performed at 1100 • C for 300 s, 900 s and 2700 s. A strong chemical interaction occurs, generating intermetallic compounds at the interface. Molten aluminum interacts exclusively with the ferritic phase due to its much higher diffusivity in this phase coupled with its marked ferrite-stabilizer behavior. Thus, the influence of cold working is not remarkable, since the strains are mainly allocated by austenitic phase. The diffusivity of aluminum increases due to lattice defects thermally generated and, mainly, to influence given by grain boundaries, multiplied by secondary austenite precipitation, which act as short-circuit diffusion paths. Ni and Cr contents in the ferritic matrix have an influence but not highly relevant. Then, the best starting condition of the super duplex stainless steel substrates, to obtain a thick interfacial layer, are the thermal annealing at 1080 • C for 360 s/mm after a solution thermal treatment at 1300 • C for 60 s/mm.

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“…The thicknesses of the IMC formed at the interface are 3 μm and 7.5 μm in the zone 1 and zone 2, respectively. Also, from EDS results, according to Al/Fe phase diagram [8], it can know the phases formed at the interface by the weight or atomic percentage of each element (Al/Fe). The IMC phase formed at the interface on both the zones is FeAl3.…”

Section: Mechanical Properties and Microstructure Of Dissimilar Frictmentioning

confidence: 99%

“…These IMCs destroy mechanical properties of the joint [7]. According to Al-Fe phase diagrams, there are many IMCs may be formed during the process such as Fe2Al5, FeAl3 and FeAl2 [8]. To overcome these welding problems, it should weld this joint without melting.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Microstructure of Dissimilar Friction Stir Welding of Pure Aluminum to Low Carbon Steel

et al. 2018

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The purpose of this research is to use friction stir welding (FSW) to join dissimilar metals, annealed low carbon steel and A1050 pure aluminum. A butt joint with a similar sheet thickness of 1.9 mm was applied. The novelties of the research are relatively using high generated heat produced by a combination of low traverse speed and high rotational speed to perform the dissimilar joints and using a tool material (K107cold work tool steel) which has not been used in FSW with tool cooling. The present work studied the effect of FSW variables such as tilt angle, tool cooling, base metal location on mechanical properties. Tensile tests were used to evaluate the mechanical properties of the dissimilar joints. The microstructure specimens were examined using a scanning electron microscope (SEM). Sound dissimilar joints were successfully produced. The maximum joint efficiency obtained in this study is 51.7% of the aluminum tensile strength. The microstructure images showed that many steel fragments were sheared off from the steel surface by the tool action and scattered in the weld nugget, a continuous intermetallic compound (IMC) layer formed at the interface, the thickness of the IMC layer at the interface decreased in the thickness direction of the weld. FeAl3 IMC phase was only observed at the interface.

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The Al-Rich Part of the Fe-Al Phase Diagram

Cited by 213 publications

References 25 publications

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅

Hot-Dip Aluminizing on AISI F55–UNS S32760 Super Duplex Stainless Steel Properties: Effect of Thermal Treatments

Mechanical Properties and Microstructure of Dissimilar Friction Stir Welding of Pure Aluminum to Low Carbon Steel

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The Al-Rich Part of the Fe-Al Phase Diagram

Cited by 213 publications

References 25 publications

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe2Al5

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe2Al5

Hot-Dip Aluminizing on AISI F55–UNS S32760 Super Duplex Stainless Steel Properties: Effect of Thermal Treatments

Mechanical Properties and Microstructure of Dissimilar Friction Stir Welding of Pure Aluminum to Low Carbon Steel

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Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅

Principles of weakly ordered domains in intermetallics: the cooperative effects of atomic packing and electronics in Fe₂Al₅