First principle calculations of the κ-Fe3AlC perovskite and iron–aluminium intermetallics

Connétable, Damien; Maugis, Philippe

doi:10.1016/j.intermet.2007.09.011

Cited by 77 publications

(59 citation statements)

References 42 publications

(38 reference statements)

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“…1 kJ/mol is compensated by the stabilization effect due to C insertion, yielding the perovskite E2 1 -Fe 3 AlC, commonly known as κ-carbide (Figure 1). Our calculations of the lattice parameter, total energy, and the local magnetic moments as given in Table 1 agree well with other calculations [35][36][37].…”

Section: Stoichiometric Phases Of L1 2 and E2 1 Symmetrysupporting

confidence: 89%

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

Timmerscheidt

Dey

Bogdanovski

et al. 2017

Metals

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Abstract:Since the addition of Al to high-Mn steels is known to reduce their sensitivity to hydrogen-induced delayed fracture, we investigate possible trapping effects connected to the presence of Al in the grain interior employing density-functional theory (DFT). The role of Al-based precipitates is also investigated to understand the relevance of short-range ordering effects. So-called E2 1 -Fe 3 AlC κ-carbides are frequently observed in Fe-Mn-Al-C alloys. Since H tends to occupy the same positions as C in these precipitates, the interaction and competition between both interstitials is also investigated via DFT-based simulations. While the individual H-H/C-H chemical interactions are generally repulsive, the tendency of interstitials to increase the lattice parameter can yield a net increase of the trapping capability. An increased Mn content is shown to enhance H trapping due to attractive short-range interactions. Favorable short-range ordering is expected to occur at the interface between an Fe matrix and the E2 1 -Fe 3 AlC κ-carbides, which is identified as a particularly attractive trapping site for H. At the same time, accumulation of H at sites of this type is observed to yield decohesion of this interface, thereby promoting fracture formation. The interplay of these effects, evident in the trapping energies at various locations and dependent on the H concentration, can be expressed mathematically, resulting in a term that describes the hydrogen embrittlement.

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Section: Stoichiometric Phases Of L1 2 and E2 1 Symmetrysupporting

confidence: 89%

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

Timmerscheidt

Dey

Bogdanovski

et al. 2017

Metals

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“…Therefore, this phase was likely formed first by the diffusion of Al in steel. It has been reported that Fe 3 Al is adsorbed in the lattice in an atmosphere with high C concentration and is transformed into the Fe 3 AlC (κ) phase with the same cubic crystal system (space group: Pm3m) [29][30][31]. Carbon decomposed from cementite in steel was not dissolved in the Fe 2 Al 5 (η) phase and was released.…”

Section: Discussionmentioning

confidence: 99%

Microstructural Evolution of Intermetallic Compound Formed in Boron Steel Hot-Dipped in Al–7%Ni Alloy

Yun

Lee

Kwak

et al. 2017

Metals

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Abstract:The microstructural evolution of the intermetallic compound (IMC) layer formed on and in boron steel that was hot dipped in an Al-7Ni (wt %) bath at 690 • C for 30-180 s was investigated, and the growth mechanism of the IMC was identified. Except for the solidification structure of Al, the reaction layer consisted of one layer on the steel surface and two layers in the steel interior. The reaction phase formed on the original surface of the steel was the Al 9 FeNi (T) phase, which has a monoclinic (space group: P21/c) crystal structure. The reaction phase formed from the T phase was the Fe 2 Al 5 (η) phase, which is orthorhombic (space group: Cmcm). The variation in thickness of the η phase increased linearly with increasing dipping time, which is in accordance with the diffusion growth, a growth mechanism of the η phase in Al-coated pure Fe and low-carbon steels. The Fe 3 AlC (κ) phase (which had a band shape with a width of 100 nm) and a cubic system were formed along the interface between the Fe2Al5 (η) phase and the steel.

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“…However, Mn 2 AlC is very close to thermodynamic stability with H cp being just +0.005 eV/atom. Here, the most competing phases, out of all the phases included, 23 are identified as Mn 3 AlC, MnAl, and C. Fe 2 AlC is found to be quite metastable with H cp = +0.116 eV/atom, and it should decompose into the inverse perovskite, Fe 3 AlC, 25,26 in combination with FeAl and C. The discrepancy with previously reported results on this system 14 highlights the need to include all competing phases in phase stability studies. The trend in increasing instability is continued with Co 2 AlC, where the most competitive phases are CoAl, Co, and C. As H cp is comparatively large for all phases with n = 2 and 3, they will not be further discussed in this work.…”

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confidence: 98%

Magnetic nanoscale laminates with tunable exchange coupling from first principles

et al. 2011

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The M(n+1)AX(n) (MAX) phases are nanolaminated compounds with a unique combination of metallic and ceramic properties, not yet including magnetism. We carry out a systematic theoretical study of potential magnetic MAX phases and predict the existence of stable magnetic (Cr(1-x)Mn(x))(2)AlC alloys. We show that in this system ferromagnetically ordered Mn layers are exchange coupled via nearly nonmagnetic Cr layers, forming an inherent structure of atomic-thin magnetic multilayers, and that the degree of disorder between Cr and Mn in the alloy can be used to tune the sign and magnitude of the coupling

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First principle calculations of the κ-Fe3AlC perovskite and iron–aluminium intermetallics

Cited by 77 publications

References 42 publications

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

The Role of κ-Carbides as Hydrogen Traps in High-Mn Steels

Microstructural Evolution of Intermetallic Compound Formed in Boron Steel Hot-Dipped in Al–7%Ni Alloy

Magnetic nanoscale laminates with tunable exchange coupling from first principles

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