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应用三维元胞自动机模型模拟了Al-3Cu-1Mg合金的树枝晶组织,研究了溶质互扩散对枝晶组织的影响。采用两种方式处理溶质扩散系数:(1)溶质扩散系数与溶质成分和温度有关,不考虑溶质互扩散系数;(2)耦合计算溶质扩散矩阵,即考虑溶质互扩散的影响。结果表明,枝晶尖端选择参数比边缘稳定性理论给出的值小。由于Al-Cu-Mg体系中两种合金元素的相互吸引作用,在溶质互扩散时,枝晶尖端生长速度较小,而尖端半径较大。
The dendrite structure of Al-3Cu-1Mg alloy was simulated by using the three-dimensional cellular automaton model. The effect of solute diffusion on the dendritic structure was studied. Solute diffusion coefficients are handled in two ways: (1) Solute diffusion coefficients are related to solute composition and temperature, regardless of solute diffusion coefficients; and (2) Solute diffusion matrix is coupled to account for the effect of solute diffusion. The results show that the dendritic tip selection parameter is smaller than the value given by edge stability theory. Due to the mutual attraction of the two alloying elements in the Al-Cu-Mg system, the dendrite tip growth rate is smaller and the tip radius is larger when the solute interdiffusion.