COMPUTER-SIMULATION OF PHASE-DECOMPOSITION OF AL-ZN AND FE-MO ALLOYS BASED UPON THE NONLINEAR DIFFUSION EQUATION

Computer simulations of phase decomposition are performed on the basis of the Cahn-Hilliard's two-dimensional non-linear diffusion equation for Al-Zn and Fe-Mo binary alloys where the mottled and the modulated structures are formed during ageing. In the calculation, the modified regular solution approximation was adopted, i.e. the composition and temperature dependencies of the interaction parameter OMEGA was taken into account and the anisotropic elastic strain energy was also considered. The phase decomposition is successfully computed for Al-Zn and Fe-Mo alloys. The morphologies of the calculated microstructures are in good agreement with those of the experimentally obtained microstructures for both alloys. Moreover, the values of the mean wavelength of the calculated microstructures agree well with those of the experimentally obtained ones.