混合急冷された過共晶Al–Si合金の初晶凝固に及ぼす対流混合の影響

抄録

The mixing-crystallization model has been used to evaluate the effects ofthe convective mixing on the undercooling and solidification behavior of a hypereutectic Al–Si alloy during the mixing process of two different molten alloys: the first melt (Al–12 mass%Si alloy) and the second melt (Al–32 mass%Si alloy). This model treats the mixing of these alloys in stretching lamellar configurations to consider the interactions between the fluid clumps ofthe second melt. The obtained results are summarized as follows: (1) The undercooling of the second melt in the lamellar configurations are smaller than that in the single slab configuration because of the interactions between the second melt lamellar. (2) The number of primary crystals is maximized at a certain strain rate of stretching lamellar depending on the initial melt-distribution. Therefore, excessive agitation during the initial stage of the solidification may depress the refinement of the primary crystals. (3) Nonuniform distribution of lamellar thickness is effective for the crystal refinement compared with the uniform one.