Precipitation of paraequilibrium cementite: Experiments, and thermodynamic and kinetic modeling

G. Ghosh; G. B. Olson

doi:10.1016/S1359-6454(02)00054-X

Precipitation of paraequilibrium cementite: Experiments, and thermodynamic and kinetic modeling

G. Ghosh^*, G. B. Olson

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

108 Scopus citations

Abstract

The precipitation of cementite prior to the precipitation of the strengthening M₂C phase is investigated using two model ultra-high strength (UHS) steels. The structure, microstructure and chemical composition of cementite are studied by analytical electron microscopy techniques. The structure of cementite precipitated during early stages of tempering at 755 and 783 K was confirmed by convergent beam electron diffraction. In an alloy containing 0.16 mass% C, the cementite particles were primarily plate shaped and interlath type, whereas in an alloy containing 0.247 mass% C both inter- and intralath particles were observed. Consistent with the earlier studies on tempering of Fe-C martensite, lattice imaging of cementite suggests microsyntactic intergrowth of M₅C₂ (Hägg carbide). Quantification of the substitutional elements in cementite confirms its paraequilibrium state with ferrite at the very early stage of tempering. Computational thermodynamic and kinetic tools, Thermo-Calc and DICTRA (DIffusion controlled TRAnsformation) software, respectively, are used to model the precipitaton of paraequilibrium cementite in several multicomponent alloys. A thermodynamic model parameter describing the effect of Si on the stability of cementite is proposed. The model parameter is consistent with the following results: (a) that Si does not partition to cementite in Fe-Si-C and Co-Si-C alloys under orthoequilibrium conditions, and (b) there is a large driving force for the precipitation of paraequilibrum cementite in an Fe-0.41C-3Mn-2Si alloy where it has been experimentally verified. The nucleation driving forces for the precipitation of paraequilibrium cementite, and the two-phase (ferrite and cementite) paraequilibrium boundaries for multicomponent alloys are calculated using the Thero-Calc software systems. The results of growth simulations of cementite under paraequilibrium condition in multicomponent systems using the DICTRA software are also presented.

Original language	English (US)
Pages (from-to)	2099-2119
Number of pages	21
Journal	Acta Materialia
Volume	50
Issue number	8
DOIs	https://doi.org/10.1016/S1359-6454(02)00054-X
State	Published - May 8 2002

Keywords

Analytical electron microscopy
Cementite
Kinetics
Thermodynamics

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Ceramics and Composites
Polymers and Plastics
Metals and Alloys

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10.1016/S1359-6454(02)00054-X

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title = "Precipitation of paraequilibrium cementite: Experiments, and thermodynamic and kinetic modeling",

abstract = "The precipitation of cementite prior to the precipitation of the strengthening M2C phase is investigated using two model ultra-high strength (UHS) steels. The structure, microstructure and chemical composition of cementite are studied by analytical electron microscopy techniques. The structure of cementite precipitated during early stages of tempering at 755 and 783 K was confirmed by convergent beam electron diffraction. In an alloy containing 0.16 mass% C, the cementite particles were primarily plate shaped and interlath type, whereas in an alloy containing 0.247 mass% C both inter- and intralath particles were observed. Consistent with the earlier studies on tempering of Fe-C martensite, lattice imaging of cementite suggests microsyntactic intergrowth of M5C2 (H{\"a}gg carbide). Quantification of the substitutional elements in cementite confirms its paraequilibrium state with ferrite at the very early stage of tempering. Computational thermodynamic and kinetic tools, Thermo-Calc and DICTRA (DIffusion controlled TRAnsformation) software, respectively, are used to model the precipitaton of paraequilibrium cementite in several multicomponent alloys. A thermodynamic model parameter describing the effect of Si on the stability of cementite is proposed. The model parameter is consistent with the following results: (a) that Si does not partition to cementite in Fe-Si-C and Co-Si-C alloys under orthoequilibrium conditions, and (b) there is a large driving force for the precipitation of paraequilibrum cementite in an Fe-0.41C-3Mn-2Si alloy where it has been experimentally verified. The nucleation driving forces for the precipitation of paraequilibrium cementite, and the two-phase (ferrite and cementite) paraequilibrium boundaries for multicomponent alloys are calculated using the Thero-Calc software systems. The results of growth simulations of cementite under paraequilibrium condition in multicomponent systems using the DICTRA software are also presented.",

keywords = "Analytical electron microscopy, Cementite, Kinetics, Thermodynamics",

author = "G. Ghosh and Olson, {G. B.}",

note = "Funding Information: This work was supported by the National Science Foundation under Grant No. DMR-9806749 and General Motors Academic Partnership Master Agreement, 2001. Copyright: Copyright 2008 Elsevier B.V., All rights reserved.",

year = "2002",

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doi = "10.1016/S1359-6454(02)00054-X",

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TY - JOUR

T1 - Precipitation of paraequilibrium cementite

T2 - Experiments, and thermodynamic and kinetic modeling

AU - Ghosh, G.

AU - Olson, G. B.

N1 - Funding Information: This work was supported by the National Science Foundation under Grant No. DMR-9806749 and General Motors Academic Partnership Master Agreement, 2001. Copyright: Copyright 2008 Elsevier B.V., All rights reserved.

PY - 2002/5/8

Y1 - 2002/5/8

N2 - The precipitation of cementite prior to the precipitation of the strengthening M2C phase is investigated using two model ultra-high strength (UHS) steels. The structure, microstructure and chemical composition of cementite are studied by analytical electron microscopy techniques. The structure of cementite precipitated during early stages of tempering at 755 and 783 K was confirmed by convergent beam electron diffraction. In an alloy containing 0.16 mass% C, the cementite particles were primarily plate shaped and interlath type, whereas in an alloy containing 0.247 mass% C both inter- and intralath particles were observed. Consistent with the earlier studies on tempering of Fe-C martensite, lattice imaging of cementite suggests microsyntactic intergrowth of M5C2 (Hägg carbide). Quantification of the substitutional elements in cementite confirms its paraequilibrium state with ferrite at the very early stage of tempering. Computational thermodynamic and kinetic tools, Thermo-Calc and DICTRA (DIffusion controlled TRAnsformation) software, respectively, are used to model the precipitaton of paraequilibrium cementite in several multicomponent alloys. A thermodynamic model parameter describing the effect of Si on the stability of cementite is proposed. The model parameter is consistent with the following results: (a) that Si does not partition to cementite in Fe-Si-C and Co-Si-C alloys under orthoequilibrium conditions, and (b) there is a large driving force for the precipitation of paraequilibrum cementite in an Fe-0.41C-3Mn-2Si alloy where it has been experimentally verified. The nucleation driving forces for the precipitation of paraequilibrium cementite, and the two-phase (ferrite and cementite) paraequilibrium boundaries for multicomponent alloys are calculated using the Thero-Calc software systems. The results of growth simulations of cementite under paraequilibrium condition in multicomponent systems using the DICTRA software are also presented.

AB - The precipitation of cementite prior to the precipitation of the strengthening M2C phase is investigated using two model ultra-high strength (UHS) steels. The structure, microstructure and chemical composition of cementite are studied by analytical electron microscopy techniques. The structure of cementite precipitated during early stages of tempering at 755 and 783 K was confirmed by convergent beam electron diffraction. In an alloy containing 0.16 mass% C, the cementite particles were primarily plate shaped and interlath type, whereas in an alloy containing 0.247 mass% C both inter- and intralath particles were observed. Consistent with the earlier studies on tempering of Fe-C martensite, lattice imaging of cementite suggests microsyntactic intergrowth of M5C2 (Hägg carbide). Quantification of the substitutional elements in cementite confirms its paraequilibrium state with ferrite at the very early stage of tempering. Computational thermodynamic and kinetic tools, Thermo-Calc and DICTRA (DIffusion controlled TRAnsformation) software, respectively, are used to model the precipitaton of paraequilibrium cementite in several multicomponent alloys. A thermodynamic model parameter describing the effect of Si on the stability of cementite is proposed. The model parameter is consistent with the following results: (a) that Si does not partition to cementite in Fe-Si-C and Co-Si-C alloys under orthoequilibrium conditions, and (b) there is a large driving force for the precipitation of paraequilibrum cementite in an Fe-0.41C-3Mn-2Si alloy where it has been experimentally verified. The nucleation driving forces for the precipitation of paraequilibrium cementite, and the two-phase (ferrite and cementite) paraequilibrium boundaries for multicomponent alloys are calculated using the Thero-Calc software systems. The results of growth simulations of cementite under paraequilibrium condition in multicomponent systems using the DICTRA software are also presented.

KW - Analytical electron microscopy

KW - Cementite

KW - Kinetics

KW - Thermodynamics

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DO - 10.1016/S1359-6454(02)00054-X

M3 - Article

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SN - 1359-6454

VL - 50

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EP - 2119

JO - Acta Materialia

JF - Acta Materialia

IS - 8

ER -

Precipitation of paraequilibrium cementite: Experiments, and thermodynamic and kinetic modeling

Abstract

Keywords

ASJC Scopus subject areas

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