Abstract
The isothermal dendrite growth process in an Al–Zn binary alloy was simulated using the phase-field method. It was clarified that the larger the super cooling was, the finer the dendrite structure became. In addition, the relationships between the growth velocity of the primary dendrite arm (V) and the dimensionless super cooling (Δ) and between the radius of the primary dendrite arm (d) and the dimensionless super cooling (Δ) were qualitatively clarified from a viewpoint of the scaling theory. A comparative study between the phase-field method and the dendrite growth theory was also performed by utilizing the previous data of the Al–Cu alloy and the present data of the Al–Zn alloy. The growth velocity of the primary dendrite arm (V) , the radius of the primary dendrite arm (R) and the solute distribution at a solid-liquid interface were determined and compared. The values showed that the agreement between the phase-field simulation and the dendrite growth theory was good if the shape of a dendrite tip was parabolic. In a region with large super cooling, where the growth mode changes from a dendrite to cell, the dendrite growth theory becomes invalid.
