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Analytical treatment of diffusion during precipitate growth in multicomponent systems
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
2008 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 56, no 8, 1890-1896 p.Article in journal (Refereed) Published
Abstract [en]

We propose an approximate growth rate equation that takes into account both cross-diffusion and high supersaturations for modeling precipitation in multicomponent systems. We then apply it to an Fe-alloy in which interstitial C atoms diffuse much faster than substitutional solutes, and predict a spontaneous transition from slow growth under ortho-equilibrium to fast growth under the non-partitioning local equilibrium condition. The transition is caused by the decrease in the Gibbs-Thomson effect as the growing particle becomes larger. The results agree with DICTRA simulations where full diffusion fields are calculated.

Place, publisher, year, edition, pages
2008. Vol. 56, no 8, 1890-1896 p.
Keyword [en]
precipitation, diffusion, kinetics, thermodynamics, NPLE, alloys, transformations, kinetics
URN: urn:nbn:se:kth:diva-17541DOI: 10.1016/j.actamat.2007.12.037ISI: 000255993800024ScopusID: 2-s2.0-41849090445OAI: diva2:335585
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-03-16Bibliographically approved
In thesis
1. Simulation of Phase Transformations and coarsening: Computational tools for alloy development
Open this publication in new window or tab >>Simulation of Phase Transformations and coarsening: Computational tools for alloy development
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The final properties of an alloy are highly interlaced with its microstructure. It is therefore essential to control the evolution of the microstructure of the material during the fabrication process. Nowadays, materials design involves an increasing part of computational design to complement the traditional experimental trial and error approach. Such simulations of the process can decrease the number of material prototypes and shorten the development time for new alloys.

In this thesis several microstructure models, aimed for process design, have been suggested. The ambition has been to develop physically based models that are capable to represent the evolution of hundreds of grain or particle sizes, where the models should be possible to run on a standard computer with simulation times less than one day. To achieve this goal, simplified approaches have been suggested, which are accurate enough for the growth rate of grains and particles. The microstructure models have all in common that size distributions of grains or particles are simulated with mean-field approaches. Several of the models also utilize composition and temperature dependent thermodynamic and kinetic properties continually throughout the simulations. These properties have been calculated with programming interfaces to Thermo-Calc and DICTRA together with appropriate thermodynamic and kinetic databases. The materials that have been considered in the present thesis are low alloyed steels, aluminium alloys and cemented carbides. The models are however generic in the sense that all materials can be handled if appropriate thermodynamic, kinetic and property databases exist for the alloy.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. iv, 40 p.
National Category
Materials Engineering
urn:nbn:se:kth:diva-31454 (URN)978-91-7415-891-5 (ISBN)
Public defence
2011-03-25, F3, Lindstedtsvägen 28, KTH, Stockholm, 13:00 (English)
QC 20110316Available from: 2011-03-16 Created: 2011-03-16 Last updated: 2011-03-16Bibliographically approved

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