A simulation method based on a diffuse-interface-flux model is proposed for the pattern formation during crystal growth. A numerical scheme was extended for the general treatment of solidification from simple analytical conditions. A diffuse interface with width delta is assumed between the solid and liquid phases. The molar flux between solid and liquid is balanced at the diffuse interface layer Lis a field of diffusion. The shape of the interface proceeds under the phase transition of the interface layer to solid or liquid. To ascertain the validity of the method, uniaxial solidifications of dilute binary alloy were simulated to observe sonic morphological transitions from planner to cellular interface. The wavelengths of cellular interface agree well with those from the Mullins-Sekerka model. (C) 2002 Elsevier Science B.V. All rights reserved.