采用热力学计算技术，以Al-0.3%Si-0.1%Cu(质量分数)三元合金为例，分析了合金相图特征参数，讨论了采 用热力学计算技术所得参数和线性化参数在凝固过程中固/液界面线性稳定性和非线性稳定性判断上的差异， 给出了 固/液界面稳定性区域、非稳定性区域及亚临界分叉区域。 结果表明，采用热力学计算所得相图特征参数随温度变化而 变化，而非线性化参数为定值，通过该参数所获得的稳定区域较线性化参数所得稳定区域小，判断固/液界面稳定性更 严苛，且只有在扰动频率很大或者很小时，热力学计算所得参数和线性化参数才可以互相替代，此时对于最终固/液界 面稳定性判断影响不大。

The morphological linear stability and nonlinear stability of the solid-liquid interface of an Al-0.3 wt.% Si-0.1 wt.% Cu ternary alloy were investigated via thermodynamics methods. Typical parameters of the phase diagram and different stable regions between the linear stability and nonlinear stability of the solid-liquid interface were discussed via two parameters, which were calculated via the thermodynamic method and the linear parameter method, respectively. The stable regions, unstable regions, and subcritical bifurcation regions of the solid-liquid interface are also presented. The results reveal that the typical parameters of the phase diagram obtained via thermodynamic calculations vary with temperature rather than being linear parameters with constant values. The stable regions calculated by coupling with the thermodynamic method are less than those calculated by linear parameters under the conditions of either linear stability or nonlinear stability theory, and the judgment of solid-liquid interface instability is more stringent. When the perturbation frequency is large enough or small enough, the parameters obtained via thermodynamic calculation and linearized parameters can be substituted for each other, with little impact on the final judgment of solid-liquid interface stability.