Direct evidence for the formation of ordered carbides in a ferrite-based low-density Fe–Mn–Al–C alloy studied by transmission electron microscopy and atom probe tomography

Seol, Jae Bok; Raabe, Dierk; Choi, Pyuck‐Pa; Park, Hyung-Seok; Kwak, Jai Hyun; Park, Chan-Gyung

doi:10.1016/j.scriptamat.2012.08.013

Cited by 134 publications

(63 citation statements)

References 27 publications

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“…3 . In comparison, the composition of the lamellar j-carbide in a study by Seol et al [29] of a mostly ferritic alloy was found to be (Fe,Mn) 3 (Fe,Al)C x=0.7 as measured by APT. Utilizing X-ray diffraction and an empirical relationship for the amplitude of spinodal decomposition, Sato et al [6] calculated a j-carbide composition of (Fe,Mn) 3 AlC x=0.…”

Section: Discussionmentioning

confidence: 81%

“…pct) steel. [29] In addition, Acelrad et al [8] reported that the addition of silicon produces a partitioning of manganese from the austenite matrix into grain boundary j-carbide during aging and a study by Ishida et al [48] found evidence of homogeneously nucleated j-carbide with a manganese composition 2 to 5 pct greater than the austenite matrix. However, in the current study, the manganese distribution across the interface of the matrix austenite and the j-carbide shows that the j-carbide is depleted of Mn as shown in Figures 8(a) and (d) and the partitioning coefficient for manganese was determined to be 0.9, meaning slight partitioning of manganese to the austenite matrix.…”

Section: Discussionmentioning

confidence: 99%

“…However, in the current study, the manganese distribution across the interface of the matrix austenite and the j-carbide shows that the j-carbide is depleted of Mn as shown in Figures 8(a) and (d) and the partitioning coefficient for manganese was determined to be 0.9, meaning slight partitioning of manganese to the austenite matrix. In their study of a mostly ferritic alloy, it was suggested by Seol et al [29] that the neighboring phase controls the partitioning of manganese and aluminum in j-carbide. The study by Ishida confirms this to a degree and although they show slight partitioning of manganese into the homogeneous j-carbide of austenitic alloys, they show significant partitioning of manganese, up to 15 pct greater, when the neighboring phase to the j-carbide is ferrite.…”

Section: Discussionmentioning

confidence: 99%

“…pct) steel. [29] j-carbides were found to be manganese rich with an aluminum concentration that was close in composition to the adjoining ferrite. They suggest that manganese substitution for iron would make the j-carbide harder and stronger because of stronger bonding between Mn-C couples in comparison to Fe-C pairs.…”

Section: Introductionmentioning

confidence: 98%

See 3 more Smart Citations

An Atom Probe Study of Kappa Carbide Precipitation and the Effect of Silicon Addition

Bartlett

Aken

Medvedeva

et al. 2014

Metall Mater Trans A

101

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The influence of silicon on j-carbide precipitation in lightweight austenitic Fe-30Mn-9Al-(0.59-1.56)Si-0.9C-0.5Mo cast steels was investigated utilizing transmission electron microscopy, 3D atom-probe tomography, X-ray diffraction, ab initio calculations, and thermodynamic modeling. Increasing the amount of silicon from 0.59 to 1.56 pct Si accelerated formation of the j-carbide precipitates but did not increase the volume fraction. Silicon was shown to increase the activity of carbon in austenite and stabilize the j-carbide at higher temperatures. Increasing the silicon from 0.59 to 1.56 pct increased the partitioning coefficient of carbon from 2.1 to 2.9 for steels aged 60 hours at 803 K (530°C). The increase in strength during aging of Fe-Mn-Al-C steels was found to be a direct function of the increase in the concentration amplitude of carbon during spinodal decomposition. The predicted increase in the yield strength, as determined using a spinodal hardening mechanism, was calculated to be 120 MPa/wt pct Si for specimens aged at 803 K (530°C) for 60 hours and this is in agreement with experimental results. Silicon was shown to partition to the austenite during aging and to slightly reduce the austenite lattice parameter. First-principles calculations show that the Si-C interaction is repulsive and this is the reason for enhanced carbon activity in austenite. The lattice parameter and thermodynamic stability of j-carbide depend on the carbon stoichiometry and on which sublattice the silicon substitutes. Silicon was shown to favor vacancy ordering in j-carbide due to a strong attractive Si-vacancy interaction. It was predicted that Si occupies the Fe sites in nonstoichiometric j-carbide and the formation of Si-vacancy complexes increases the stability as well as the lattice parameter of j-carbide. A comparison of how Si affects the enthalpy of formation for austenite and j-carbide shows that the most energetically favorable position for silicon is in austenite, in agreement with the experimentally measured partitioning ratios.

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

An Atom Probe Study of Kappa Carbide Precipitation and the Effect of Silicon Addition

Bartlett

Aken

Medvedeva

et al. 2014

Metall Mater Trans A

101

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show abstract

“…This is ferritic-matrix-based () but may contain a fraction of . In addition to  phase formed by the spinodal/eutectoid decomposition,  precipitates may form at the austenite grain boundaries after long annealing periods [11]. The steels with high Mn low Al and high Mn no Al are found free from , with  matrix and in excellent formability 3 [12][13].…”

Section: Introductionmentioning

confidence: 99%

Influence of κ-carbide interface structure on the formability of lightweight steels

Qin

2016

Materials & Design

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Abstractκ-carbide () in high aluminium (Al) steels is grown from austenite () via + or α+ ( represents ferrite), and is a lamellar structure. This work demonstrates that the formability of high Al lightweight steels is affected by the lattice misfit and interface shape between  and matrix. The cold workability can be improved by either to change the steel chemical constitution or to implement an electro-thermo-mechanical process. For ferrite-matrix-based high Al steel, electric-current promotes the spheroidization and refinement of  structure and reduces volume fraction of  phase. This retards the crack nucleation and propagation, and hence improves the materials formability. The observation is caused by a direct effect of electric-current rather than side effects.

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Effect of Al Content on the Microstructure and Mechanical Properties of the Sintered Fe–Mn–Al Porous Steel

Wang,

Zhang,

Liang

et al. 2023

Adv Eng Mater

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Al content is of great importance for the evolution of the microstructure and compressive performance of the high‐Mn and high‐Al porous steels. Herein, Fe–Mn–Al porous steels with different Al contents are prepared via powder sintering at different temperatures. The results show that the main phases of the sintered samples at 640 °C are α‐Fe, α‐Mn, and Al, while a small amount of Fe2Al5 and Al8Mn5 exists in the samples with 15 and 20 wt% Al. At 1200 °C, the sintered sample with 5 wt% Al is composed of γ‐Fe, while those with 15 and 20 wt% Al are mainly α‐Fe. The length of Mn depletion region and porosity of the samples increase with the increase of Al content. The largest total and open porosity are observed in the 1200 °C‐sintered sample with 20 wt% Al, which are 63.1 and 60.7 vol%, respectively. The compressive strength decreases sharply from 770 MPa for the sample with 5 wt% Al to 7.5 MPa with 15 wt% Al, after sintering at 1200 °C. Ductile fracture occurs in the sample with 5 wt% Al, while brittle fracture is the main fracture mode in those with 15 and 20 wt% Al.

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Direct evidence for the formation of ordered carbides in a ferrite-based low-density Fe–Mn–Al–C alloy studied by transmission electron microscopy and atom probe tomography

Cited by 134 publications

References 27 publications

An Atom Probe Study of Kappa Carbide Precipitation and the Effect of Silicon Addition

An Atom Probe Study of Kappa Carbide Precipitation and the Effect of Silicon Addition

Influence of κ-carbide interface structure on the formability of lightweight steels

Effect of Al Content on the Microstructure and Mechanical Properties of the Sintered Fe–Mn–Al Porous Steel

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