Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Computer simulation of diffusion controlled transformations in multicomponent alloys
KTH, Superseded Departments, Materials Science and Engineering.
1997 (English)Doctoral thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH , 1997. , 17 p.
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:kth:diva-2481ISBN: 91-7170-790-5 (print)OAI: oai:DiVA.org:kth-2481DiVA: diva2:8071
Public defence
1997-03-01, 00:00
Note
QC 20100617Available from: 2000-01-01 Created: 2000-01-01 Last updated: 2010-06-17Bibliographically approved
List of papers
1. On the numerical treatment of moving boundary problems
Open this publication in new window or tab >>On the numerical treatment of moving boundary problems
Show others...
1992 (English)In: Zeitschrift für Metallkunde, ISSN 0044-3093, Vol. 83, no 9, 673-678 p.Article in journal (Refereed) Published
Abstract [en]

Some numerical methods for solving a Stefan problem are discussed and compared with the exact solution. The growth of a planar particle from a supersaturated solution (or solidification from a supercooled liquid) is considered. It is found that the Murray-Landis method, based on a finite difference technique to solve the diffusion equation on a contracting grid, yields a poor accuracy for high supersaturations. The enthalpy method, also based on the finite difference technique and an interpolation formula for obtaining the interface position, shows a satisfactory performance at high supersaturations but a less satisfactory one at low supersaturations. It is demonstrated that the poor accuracy of the Murray-Landis method depends on the application of a less accurate flux-balance equation for finite time increments and the procedure for displacing the grid points. A modification of the Murray-Landis method is developed and is found to have superior numerical performance.

National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13389 (URN)A1992JV56100005 ()
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2017-12-12Bibliographically approved
2. On the growth of ferrite allotriomorphs in fe-c alloys
Open this publication in new window or tab >>On the growth of ferrite allotriomorphs in fe-c alloys
Show others...
1992 (English)In: Zeitschrift für Metallkunde, ISSN 0044-3093, Vol. 83, no 10, 729-738 p.Article in journal (Refereed) Published
Abstract [en]

Different geometrical models of allotriomorphic growth of ferrite in undercooled austenite are investigated by means of numerical and analytical treatments of diffusional growth under local equilibrium. The results obtained by the numerical method are compared with analytical solutions for those cases where such solutions may be derived. An excellent agreement is obtained. The numerical method is subsequently applied to simulate the experiments by Aaronson et al. and some more recent experiments by Hougardy et al.. taking into account the concentration dependence of the diffusivity of C in austenite and the most recent thermodynamic assessment of the ferrite/austenite equilibrium. Taking into account the experimental uncertainties we conclude that the growth of allotriomorphic ferrite must be essentially controlled by long-range carbon diffusion in austenite.

Keyword
KINETICS, AUSTENITE
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13390 (URN)A1992KA64500003 ()
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2017-12-12Bibliographically approved
3. Escape of carbon from ferrite plates in austenite
Open this publication in new window or tab >>Escape of carbon from ferrite plates in austenite
1993 (English)In: ACTA METALL MATER, ISSN 0956-7151, Vol. 41, no 7, 1951-1957 p.Article in journal (Refereed) Published
Abstract [en]

A newly developed computer program for the simulation of diffusional transformations has been applied to study the escape of carbon from a plate of ferrite assuming that the plate initially formed by a partitionless reaction from an Fe-C austenite. Thereafter the ferrite austenite interface was assumed to be immobile and local equilibrium was assumed for carbon but not for iron. The process first follows a parabolic rate law and is there controlled by the rate of diffusion in ferrite. Later stages are not parabolic and are controlled by the diffusivity in austenite. Its concentration dependence was taken into account. It was found that the rate could be estimated analytically using the maximum value rather than the average value.

National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13392 (URN)10.1016/0956-7151(93)90365-Y (DOI)A1993LG38200002 ()
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2010-06-17Bibliographically approved
4. AN EXPERIMENTAL AND THEORETICAL-STUDY OF CEMENTITE DISSOLUTION IN AN FE-CR-C ALLOY
Open this publication in new window or tab >>AN EXPERIMENTAL AND THEORETICAL-STUDY OF CEMENTITE DISSOLUTION IN AN FE-CR-C ALLOY
1991 (English)In: MET TRANS A-PHYS MET MATER SC, ISSN 0360-2133, Vol. 22, no 8, 1745-1752 p.Article in journal (Refereed) Published
Abstract [en]

The dissolution of cementite at 910-degrees-C in an Fe-2.06Cr-3.91C (at. pct) alloy is investigated experimentally. The Cr concentration profiles in austenite and cementite are measured by means of the scanning transmission electron microscopy/energy dispersive spectrometry (STEM/EDS) technique at different dissolution times. The measurements show the Cr enrichment in the cementite during the dissolution process. The measurements suggest that the main part of the reaction for this alloy is controlled by Cr diffusion in the cementite or in the austenite matrix. This observation is in agreement with predictions of the local equilibrium hypothesis. The carbide fraction and average particle diameter are evaluated as functions of dissolution time. The Cr enrichment of the cementite results in a supersaturation and a possible decomposition of the cementite. Microstructural evidence for such a decomposition is found by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A new program package called DICTRA,[11] which is suitable for the simulation of diffusional reactions in multicomponent alloys, has been applied to the present case. The simulation is compared with the experimental data, and a good agreement between the two is found.

Keyword
COMPUTER-SIMULATIONS, AUSTENITE, CARBON, STEEL
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13394 (URN)A1991GA56300006 ()
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2010-06-17Bibliographically approved
5. COMPUTER-SIMULATION OF DIFFUSION IN MULTIPHASE SYSTEMS
Open this publication in new window or tab >>COMPUTER-SIMULATION OF DIFFUSION IN MULTIPHASE SYSTEMS
1994 (English)In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 25, no 6, 1127-1134 p.Article in journal (Refereed) Published
Abstract [en]

A general model to treat multicomponent diffusion in multiphase dispersions is presented. The model is based on multicomponent diffusion data and basic thermodynamic data and contains no adjustable parameters. No restriction is placed on the number of components or phases that take part in the calculations, as long as the necessary thermodynamic and kinetic data are available. The new model is implemented into the DICTRA software, which makes use of THERMO-CALC to handle the thermodynamics. The model is applied to carburization of Ni alloys and heat treatment of welded joints between dissimilar materials. In both cases, the diffusion is accompanied by carbide formation or dissolution. A good agreement between experiments and calculations is found, despite the fact that no adjustable parameters are needed.

Keyword
CARBURIZATION, ALLOYS
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13395 (URN)A1994NM85400003 ()
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2017-12-12Bibliographically approved
6. Dissolution of complex carbides in austenitic stainless steels
Open this publication in new window or tab >>Dissolution of complex carbides in austenitic stainless steels
1997 (English)Report (Other academic)
Place, publisher, year, edition, pages
Stockholm: KTH, 1997
Series
Trita-MAC, 0605
National Category
Natural Sciences
Identifiers
urn:nbn:se:kth:diva-13396 (URN)
Note
QC 20100617Available from: 2010-06-17 Created: 2010-06-17 Last updated: 2010-06-17Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Höglund, Lars
By organisation
Materials Science and Engineering
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 749 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf