Kinetics of transformation of metastable silver-copper solid solutions
Metastable solid solutions were obtained at compositions across the entire range from 0 at. % Ag;Cu to 100 at. % Ag;Cu by rapid-quenching from the liquid state. Lattice parameters were measured by x-ray diffraction in Debye-Scherrer powder cameras. The enthalpy of solution of the 75.0 at. % Ag;Cu co...
| Summary: | Metastable solid solutions were obtained at compositions across the entire range from 0 at. % Ag;Cu to 100 at. % Ag;Cu by rapid-quenching from the liquid state. Lattice parameters were measured by x-ray diffraction in Debye-Scherrer powder cameras. The enthalpy of solution of the 75.0 at. % Ag;Cu composition was determined calorimetrically and is discussed in relation to the predictions of existing theories.
The process of transformation of the metastable solid solutions into the equilibrium phases was studied by means of x-ray diffraction intensity measurements, electrical resistance measurements, and optical microscopy. Results are compared with those for an alloy quenched from the solid state at a composition which exists as a solid solution at elevated temperatures. Activation energies were computed and are shown to be compatible with a diffusion controlled growth process in which most of the nuclei are present very early in the process. A model for the transformation process is postulated and discussed in terms of experimental results.
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