フェーズフィールド法によるAl–Zn合金の一方向凝固シミュレーション

抄録

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/m²]=2.78×10⁹×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.