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Nucleation, Growth and Coarsening

  • Lorenz Ratke
  • Peter W. Voorhees
Part of the Engineering Materials book series (ENG.MAT.)

Abstract

In the preceding chapters we treated growth and coarsening as separate processes. As sketched in the introduction (see chapter 1) there are several ways to prepare a two- or multi-phase system:
  1. 1.

    Nucleation from a supersaturated or supercooled liquid

     
  2. 2.

    Spinodal decomposition

     
  3. 3.

    Artificial mixing of powders

     
In the simplest picture transformations that proceed by nucleation can be divided into several steps: the nucleation process itself, followed by growth of the nuclei and finished by coarsening of the precipitates or particles or drops (in solid state transformations it is common to name the new second phase appearing in the matrix as precipitates, in transformations from a liquid to a solid they are called particles or grains and in liquid-liquid decomposition they are termed droplets). A prerequisite for the nucleation type of phase transformation is the existence of a limited miscibility in the phase diagram, see for example the eutectic phase diagram, fig.2.11, where a limited solubility exists in the solid state below the eutectic temperature. The miscibility gap in a eutectic can be described by, for example, the regular solution model. This gives the miscibility gap shown in Fig. 2.6 where the critical point does not exist since it is terminated by the eutectic reaction.

Keywords

Nucleation Rate Average Radius Critical Radius Spinodal Decomposition Diffusional Growth 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Lorenz Ratke
    • 1
  • Peter W. Voorhees
    • 2
  1. 1.Institute for Space SimulationGerman Aerospace Center DLRCologneGermany
  2. 2.Dept. of Materials Science and EngineeringNorthwestern UniversityEvanstonUSA

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