极端非平衡条件下过冷熔体枝晶生长模型

Dendrite Growth Model in Bulk Undercooled Alloy Melt

考虑界面非平衡、弯曲界面对驱动力的影响,并且摒弃液固相线线性假设,得到了界面移动热力学驱动力;从液固相线非线性条件下的动力学边界条件出发,对稳定性判据进行了修正;在溶质截留模型中,综合考虑弛豫效应和非线性液固相线的影响,对Aziz模型进行了修正;基于相图分析,得到过冷度分配。综合以上分析,在非线性液固相线基础上,得到了新的二元过冷熔体自由枝晶生长模型。将该模型应用到Ni-0.7%B合金中,结果表明无论从定性上还是定量上都与实验结果吻合得很好。

Assuming non-linear liquidus and solidus,the curvature correction was directly made to deduce the non-equilibrium interfacial driving force;Considering the kinetic boundary condition for the non-linear liquidus and solidus,an extended marginal stability criterion was deduced.The effect of curvature and relaxation were introduced in solute trapping model of Aziz.On the analysis of the phase diagram,the undercooling components were directly obtained.Then a new steady-state dendrite growth model in bulk undercooled melt was resulted for binary alloy assuming non-linear liquidus and solidus.Satisfactory agreement in quantitative and qualitative of the model prediction with the experimental data of Ni-0.7%B alloy was achieved.