Materials Transactions Online

Materials Transactions, JIM, Vol.34 No.3 (1993) pp.210-215
© 1993 The Japan Institute of Metals

Simulation of Effect of Vacancy Concentration on Anisotropy of Spinodal Decomposition

Hideyuki Ikeda* and Hidehiko Matsuda**

*Department of Mechanical Engineering, Kagoshima National College of Technology,
Kagoshima 899-51, Japan
**Department of Materials Science and Engineering, Faculty of Engineering,
Kyushu Institute of Technology, Kitakyushu 804, Japan

We have simulated the phase decomposition processes in a substitutional bcc binary alloy with a crystal anisotropy by using a Monte Carlo method combined with static variational method. The two-body Johnson-type potentials are used for the interactions between the constituents.
We have found that the difference of vacancy concentrations influences not only the growth rate of clusters but also the growth process. The spinodal decomposition took place remarkably in the relaxed alloy with higher concentration of vacancies and in the non-relaxed alloy with lower concentration. The reason for the progress of the decomposition in the relaxed alloy is that the influence of other vacancies makes the migration of the vacancy possible. Difficulty of the migration is, however, caused by some vacancies occupying certain sites, this may bring to the anisotropic decomposition. The results for the non-relaxation can be explained qualitatively by inequalities among the binding energies between constituents.

(Received September 16, 1992)

Keywords: spinodal decomposition, relaxation of lattice distortion, computer simulation, pair potential, elastic interaction, Monte Carlo method, variational method

This paper was originally published in Japanese in J. Japan Inst. Metals, 55 (1991), 909.

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© 1993 The Japan Institute of Metals