Precipitate development in steel
An in-depth study on formation and growth of a second solid phase
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Abstract
In this dissertation the formation of precipitates in steel is studied.
In the first chapter some theoretical background is presented to the topic.
Then in the second chapter an analytical approximation to the classical nucleation and growth model is presented.
In the third chapter a reference-free modified embedded atom method (RF-MEAM) potential is constructed for Fe, suitable for ferrite and austenite.
In chapter four the formation of Nb-C and Ti-C clusters in ferrite is studied, here formation paths with a monotone decrease in Gibbs energy are found. Moreover, the resulting clusters remain stable up to 1100K.
In the fifth chapter other group IV and V transition metal-carbon systems in ferrite are studied in small cells using density functional theory. Showing similar energy patterns as previously found for Nb and Ti. Furthermore the transformation from a metal-carbon cluster to a carbide precipitate is studied, where the matrix strain is found to be the driving force behind the transformation.
in the sixth and last chapter some recommendations are presented.
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