Directional solidification simulation of Al–Zn binary alloy was performed using the phase field method. The result was visualized, and the influences of Zn composition
C0, temperature gradient
G, and growth velocity
V on the stability of planar interface and crystal growth form were investigated.
With increasing growth velocity
V, the morphology of solid-liquid interface changed from planar interface to plane with hollows, and finally to cell-like segregated structure. The curvature of the tip of the cell-like structure
R became small and the spacing between the cells decreased with increasing
V. The stability region of planar interface was determined by the value of
G/
V and Zn concentration
C0. It turns out that the boundary of the stability region of planar interface is a linear function of
C0 such that
G/
V [K·s/m
2]=2.78×10
9×
C0 [at%], where the value of the slope was about 70% of that of the prediction of the constitutional undercooling theory. It was also found that the spacing between the cell-like segregated structures agrees well with the dendrite growth theory.
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