Coarsening kinetics, thermodynamic properties, and interfacial characteristics of {delta}{sup '} precipitates in Al-Li alloys taking into account the Gibbs-Thomson effect
- Nuclear Fuel and Materials Division, Institute of Nuclear Energy Research, Lungtan, Taiwan (China)
The structure factor model of small-angle x-ray scattering (SAXS) analysis is validated herein by transmission electron microscopy (TEM) result regarding the volume fraction and size of {delta}{sup '} precipitates. The kinetic behaviors of the number density and volume fraction of {delta}{sup '} precipitates in Al-Li alloys during the coarsening stage are quantitatively investigated by SAXS. The results indicate that the conventional kinetic law must be replaced by a more general equation that incorporates the Gibbs-Thomson effect and the time-dependence of the volume fraction during Ostwald ripening. This work also proposes new methods that combine the Gibbs-Thomson effect and the traditional SAXS equation to resolve more reliably and model independently the interfacial energy, the concentration of solute Li in the {alpha} matrix in equilibrium with {delta}{sup '} particles of a nanoscale radius C{sub {alpha}}{sub r}, the equilibrium solubility of the {alpha} phase C{sub e{alpha}} and the equilibrium concentration of {delta}{sup '} particles. The Gibbs-Thomson effect considers the effects of the interfacial energy and particle size on the equilibrium concentration. This effect quantitatively clarifies that the C{sub {alpha}}{sub r} value is size-dependent and is related to the C{sub e{alpha}} value and the interfacial energy. The traditional SAXS equation determines the Li concentrations in the {delta}{sup '} particles and the matrix from the measured scattering contrast. The traditionally determined solubility is in fact the C{sub {alpha}}{sub r} value and is mistakenly regarded as the equilibrium concentration C{sub e{alpha}} (corresponding to the radius is infinite). These results are compared to other results obtained by SAXS, TEM, and calculation. The time evolution of the transition interfacial layers between {delta}{sup '} particles and the matrix is extensively investigated using SAXS.
- OSTI ID:
- 20664940
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 70, Issue 17; Other Information: DOI: 10.1103/PhysRevB.70.174104; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ALLOYS
EQUILIBRIUM
KINETICS
LAYERS
LITHIUM ALLOYS
NANOSTRUCTURES
PARTICLE SIZE
PARTICLES
PRECIPITATION
SMALL ANGLE SCATTERING
SOLUBILITY
STRUCTURE FACTORS
SURFACE ENERGY
TIME DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION