Influence of strain energy on critical nucleus shape and kinetics of homogeneous fcc yields fcc nucleation
- IBM T.J. Watson Laboratory, Yorktown Heights, NY (USA)
The influence of crystallography upon critical nucleus shapes and kinetics of homogeneous fcc-fcc nucleation was studied by combining the discrete lattice non-classical model previously utilized by the authors and the microscope theory of strain energy, as used by Cook and de Fontaine in the case of compositional fluctuations in cubic lattices. This permitted simultaneous consideration of the influence of anisotropic interfacial energy and anisotropic strain energy upon nucleation. This is extremely difficult to do using other models of strain energy because of mathematical difficulties. The model is applied to nuclei of Al-Cu GP zones and homogeneously formed nuclei in Cu-Co. It is found that the plate-like shape of Al-Cu GP zones arises during nucleation because of the predominance of coherency strain energy when the misfit is high. In Cu-Co alloys, the misfit is smaller and the distortion tensor is cubic; thus the nucleus is found to remain essentially spherical. The influence of strain energy upon the kinetics of nucleation of Co-rich precipitates in a Cu-rich Cu-Co alloy is found to be very important, reducing them by as much as five orders of magnitude.
- OSTI ID:
- 5368951
- Report Number(s):
- CONF-840909--
- Journal Information:
- TMS (The Metallurgical Society) Paper Selection; (USA), Journal Name: TMS (The Metallurgical Society) Paper Selection; (USA) Vol. 56; ISSN TMPSA; ISSN 0197-1689
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
COBALT ALLOYS
COPPER ALLOYS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
CUBIC LATTICES
ENERGY
FCC LATTICES
FREE ENERGY
INTERFACES
KINETICS
MATHEMATICAL MODELS
NUCLEATION
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PRECIPITATION
SEPARATION PROCESSES
SHAPE
STRAINS
SURFACE ENERGY
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES