Time evolution of a quenched binary alloy: computer simulation of a three-dimensional model system
- Yeshiva Univ., New York
Results are presented of computer simulation of the time evolution for a model of a binary alloy, such as ZnAl, following quenching. The model system is a simple cubic lattice the sites of which are occupied either by A or B particles. There is a nearest neighbor interaction favoring segregation into an A rich and a B rich phase at low temperatures, T less than T/sub c/. Starting from a random configuration, T much greater than T/sub c/, the system is quenched to and evolves at a temperature T less than T/sub c/. The evolution takes place through exchanges between A and B atoms on nearest neighbor sites. The probability of such an exchange is assumed proportional to e/sup -..beta delta..U/ (1 + e/sup -..beta delta..U/)/sup -1/ where ..beta.. = (k/sub B/T)/sup -1/ and ..delta..U is the change in energy resulting from the exchange. In the simulations either a 30 x 30 x 30 or a 50 x 50 x 50 lattice is used with various fractions of the sites occupied by A particles. The evolution of the Fourier transform of the spherically averaged structure function S(k,t), the energy, and the cluster distribution were computed. Comparison is made with various theories of this process and with some experiments. It is found in particular that the results disagree with the predictions of the linearized Cahn-Hilliard theory of spinodal decomposition. The qualitative form of the results appear to be unaffected if the change in the positions of the atoms takes place via a vacancy mechanism rather than through direct exchanges.
- OSTI ID:
- 7330893
- Journal Information:
- Nucl. Metall.; (United States), Vol. 20; Conference: Conference on computer simulation for materials applications, Gaithersburg, MD, USA, 19 Apr 1976; Other Information: See CONF-760421--P1
- Country of Publication:
- United States
- Language:
- English
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