各向异性作用下合金定向凝固界面稳定性的渐近分析

The asymptotic analysis of interfacial stability with surface tension anisotropy for directional solidification of alloys

采用渐近分析方法对考虑了界面能各向异性的单相二元合金平界面定向凝固过程进行了线性稳定性分析,得到了特定条件下的零级、一级渐近解,并通过对长波段渐近解的讨论得出了适用于整个波段的色散关系.分析表明零级渐近解等效于成分过冷理论,而一级渐近解则与M-S稳定性理论一致.在稳定状态控制参数(抽拉速度和温度梯度)的选择图中,界面能各向异性增大了不稳定区域,且在高速和高温度梯度时的影响更强.

An asymptotic analysis of interfacial stability with the surface tension anisotropy is derived for directional solidification of alloys. The zero and first order solution for multi-scale and the zero order solution for single-scale are obtained. The dispersion relation adapted to all wave-length is presented by combining the short and the long wave-length solutions. It was concluded that the zero order asymptotic solution is equivalent to constitutional undercooling theory and the first order solution is consistent with M-S theory. The instability zone of control parameter enlarges with the surface tension anisotropy, especially for the high temperature gradient and high pulling velocitycases.