By reformulating the free energy of a system

a new phase field model is derived from closely associating the alloy phase diagram and comprehensively considering the heat transfer

solute diffusion

the anisotropy of interface energy and interface kinetics. Then the equiaxed dendritic growth of Al 7Si alloy in a undercooling melt 35 K and 50 K respectively is simulated using the new phase field model in combination with critical point plane phase field with large gradient calculation area government method that can improve calculating efficiency significantly. The some simulated results in agreement with the experimenttal resaets can be obtained. The traced tip velocities and the tip radiuses of the primary dendrite are derived from the dendrite growth process. In addition

the values of the tip velocity obtained from the simulation are in agreement with those calculated by the KGT model.