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A model was developed to describe the microstracture evolution in a directionally solidified ternary monotectic alloy.The directional solidification experiments were carried out on Al-3Pb-lSn(wt%) alloys by using a Bridgman apparatus.The microstracture evolution in the directionally solidified sample was calculated.The numerical results agree well with the experimental ones.It is demonstrated that the nucleation of the minority phase droplets occur at two different positions.One corresponds to the liquid-liquid decomposition,which occurs in front of the solidification interface.The other is at the liquid/solid interface.The nucleation rate of the minority phase droplets at the liquid/solid interface is significantly higher than at the position in front of the solidification interface.The characteristic of the nucleation process leads to a bimodal size distribution of the minority particles in the directionally solidified sample.
A model was developed to describe the microstracture evolution in a directionally solidified ternary monotectic alloy. The directional solidification experiments were carried out on Al-3Pb-lSn (wt%) alloys by using a Bridgman apparatus. Microstracture evolution in the directionally solidified sample was calculated. numerical well agree well with the experimental ones. It is said that the nucleation of the minority phase droplets occur at two different positions. It corresponds to the liquid-liquid decomposition, which occurs in the front of the solidification interface. the other is at the liquid / solid interface. nucleation rate of the minority phase droplets at the liquid / solid interface is significantly higher than at the position in front of the solidification interface. The characteristic of the nucleation process leads to a bimodal size distribution of the minority particles in the directionally solidified sample.