Modeling of primary solidification of hypereutectic Al–Si alloy with dynamic undercooling

Abstract

A simplified numerical model is proposed to simulate the crystallization behavior of facet primary crystals of a hypereutectic Al–Si alloy. The alloy is assumed to be solidified in a cooling medium which is at a given temperature, T_B. The obtained results are summarized as follows: (1) The average crystal size, d₃, decreases as cooling rate, R, increases. When R exceeds a critical level, however, d₃ begins to converge to a constant value which depends on T_B. (2) The average crystal size depends on the maximum undercooling degree of the liquid phase, ΔT_LM. (3) The value of ΔT_LM is nearly equal to ΔT_m which corresponds to the undercooling degree at the apparent onset of crystallization which is detected from the cooling curve.