First-Principles Calculations on Stabilization of Iron Carbides (Fe3C, Fe5C2, and η-Fe2C) in Steels by Common Alloying Elements

Ande, Chaitanya Krishna; Sluiter, Marcel H. F.

doi:10.1007/s11661-012-1229-y

Cited by 54 publications

(16 citation statements)

References 57 publications

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“…The lattice parameter of η-Fe 2 C has been determined from ab initio calculations by various authors [22][23][24][25], its bulk modulus has also been calculated [24,25] but the anisotropic single-crystal elastic constants have been computed only by Lv et al [25].…”

Section: Introductionmentioning

confidence: 99%

Elastic properties of eta carbide (η-Fe2C) from ab initio calculations: application to cryogenically treated gear steel

2013

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Section: Introductionmentioning

confidence: 99%

Elastic properties of eta carbide (η-Fe2C) from ab initio calculations: application to cryogenically treated gear steel

2013

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“…[30][31][32] Our recent XANES/EXAFS study of copper promoted 100Fe:5.1Si:1.25 K catalysts suggests that Cu exists in a metallic form aer activation in CO while under syngas activation, Cu was partitioned between Cu 0 and Cu 1+ . 6,15,59 In this case, Cu addition did not change the FT product selectivity, but it increased CO conversion under similar reaction conditions ( Table 2). HRTEM analysis of Co 0.7 Cu 0.3 Fe 2.0 catalyst showed less carbon growth compared to the doped catalysts.…”

Section: Fischer-tropsch Synthesismentioning

confidence: 66%

Fischer–Tropsch synthesis: effect of Cu, Mn and Zn addition on activity and product selectivity of cobalt ferrite

et al. 2016

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The effect of Cu, Mn and Zn addition on cobalt ferrite was investigated for Fischer-Tropsch synthesis (FTS).Oxalate co-precipitation followed by decomposition under inert conditions was used to obtain various metal containing cobalt ferrites (Co 0.7 M 0.3 Fe 2 O 4 ). The carburization of cobalt ferrite in flowing CO at 270 C and 175 psig yielded iron carbides (c-Fe 5 C 2 and 3 0 -Fe 2.2 C) along with a bimetallic FeCo alloy. The extent of carburization was compared among Cu, Mn, and Zn doped catalysts with undoped cobalt ferrites under similar conditions. XRD and Mössbauer spectroscopy analysis of the freshly carburized samples followed by passivation revealed that carburization of cobalt ferrite did not change appreciably with addition of Cu or Mn. On the other hand, Zn was found to retard the carburization of cobalt ferrite. Analysis of the used FT catalysts suggests that Cu is less efficient over Mn and Zn in stabilizing the iron carbides (i.e., active form of iron) during FT synthesis. The FT activity remains more or less the same for the undoped, Cu and Zn containing cobalt ferrites at higher temperatures. The CO conversion of Co 0.7 Mn 0.3 Fe 2.0 catalyst was much lower than the other catalysts tested. Addition of Zn or Mn to cobalt ferrite was found to promote alcohol formation, particularly at higher reaction temperatures. The water-gas shift activity of the catalysts was found to decrease in the following order, Co 1.0 Fe 2.0 > Co 0.7 Mn 0.3 Fe 2.0 > Co 0.7 Zn 0.3 Fe 2.0 > Co 0.7 Cu 0.3 Fe 2.0 .

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“…Clarke et al [25] also observed the existence of Mn partitioning during this temperature. The segregation of Mn from the ferrite matrix could reduce the distortion of the ferrite lattice [26], and thus the length of the specimen shrunk during this process.…”

Section: Stages In the Tempering Processmentioning

confidence: 99%

Effect of Carbide Precipitation on the Evolution of Residual Stress during Tempering

Ding

Liu

Xie

et al. 2019

Metals

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The evolution of microstructure and residual stress during the tempering of 700 L low-carbon micro-alloyed steel was studied using a crack compliance method for measuring residual stress. Additionally, a non-isothermal tempering dilatation test, Vickers micro-hardness test, and transmission electron microscopy were used. The evolution of residual stress during tempering consists of two stages. The first stage coincided with cementite precipitation. Under the initial residual stress, the transformation plasticity due to cementite precipitation leads to partial relaxation of the micro-stress evoked by the austenite-to-ferrite transformation during quenching. It also caused the material surface and the core to exhibit different residual stress evolution trends. After tempering at 300 ∘ C for 30 min, the residual stress was reduced from 487 MPa to 200 MPa; however, the elastic strain energy remained unchanged. The second stage coincided with alloy carbide precipitation and Mn partitioning, but the precipitation of the alloy carbide only reduced the elastic strain energy by 8.7%. Thus, the change in activation energy was the main reason for the relaxation of residual stress at this stage. After tempering at 600 ∘ C for 30 min, the residual stress was reduced to 174 MPa, the elastic strain energy was reduced by 72.72%, and the residual stress was controlled.

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First-Principles Calculations on Stabilization of Iron Carbides (Fe3C, Fe5C2, and η-Fe2C) in Steels by Common Alloying Elements

Cited by 54 publications

References 57 publications

Elastic properties of eta carbide (η-Fe2C) from ab initio calculations: application to cryogenically treated gear steel

Elastic properties of eta carbide (η-Fe2C) from ab initio calculations: application to cryogenically treated gear steel

Fischer–Tropsch synthesis: effect of Cu, Mn and Zn addition on activity and product selectivity of cobalt ferrite

Effect of Carbide Precipitation on the Evolution of Residual Stress during Tempering

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