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在同时考虑溶质偏析的界面法向速度依赖性与局域非平衡溶质扩散的情况下,建立一个扩展的自由枝晶生长模型。与假设等溶质界面的枝晶生长模型的预测相比,从溶质枝晶到热枝晶的转变发生在更高的过冷度,即溶质控制生长发生在更宽的过冷度区域。在高过冷度区域,从热控制生长模式到纯热控制生长模式的转变没有等溶质模型所预测的急剧,而是发生在一定范围的过冷度区域。这是由于溶质偏析的界面法向速度依赖性与局域非平衡溶质扩散这两个因素共同作用的结果。模型测试表明:本模型能够对现有Ni-0.7%B(摩尔分数)合金的实验数据给出满意的描述。
In the meantime, an extended free-dendrite growth model is established with both the normalized interface velocity dependence of solute segregation and the local unbalanced solute diffusion. The transition from solute dendrite to hot dendrite occurs at a higher degree of undercooling, ie solute-controlled growth takes place in a wider area of supercooling than predicted by the dendrite growth model at the solute interface. In the area of high subcooling, the transition from the thermally controlled growth mode to the purely thermal controlled growth mode does not take place abruptly, as predicted by the solute model, but occurs in a range of subcooling regions. This is due to the interaction between the normal velocity dependence of solute segregation and the local non-equilibrium solute diffusion. The model tests show that this model gives a satisfactory description of the experimental data of the existing Ni-0.7% B (mole fraction) alloy.