Interfacial Pattern Formation During Rapid Phase Transformations in a Binary System

合金的凝固通常发生在远离热平衡的条件下。除了分段线性非平衡热力学的传统公式外，这种快速凝固过程需要特别关注。得到的固体的微观结构和性能在很大程度上取决于凝固过程中的图案形成过程。将进行理论和实验工作。应考虑三个主要问题：(I)几个界面的传播及其相互作用，包括弹性力；(Ii)强非平衡条件下界面的快速传播；以及(Iii)向前推进的液-固界面前方流体中的相分离。我们将使用解析和数值方法，包括边界积分法和相场法。将理论模拟的结果与过冷熔体凝固前沿动力学和显微组织演变的测量结果进行了比较，结果表明过冷熔体中存在亚稳两相区。

Solidification of alloys often occurs under conditions far from thermal equilibrium. This process of rapid solidification requires special concern beyond the conventional formulations of piecewise linear non-equilibrium thermodynamics. The microstructures and thus the properties of the resulting solids are largely determined by the pattern-forming processes during solidification. Theoretical and experimental work will be performed. Three main topics shall be considered: (i) propagation of several interfaces and their interactions involving also elastic forces, (ii) fast propagation of interfaces under strong non-equilibrium conditions, and (iii) phase separation in the fluid ahead of an advancing liquid-solid interface. We will employ both analytical and numerical methods, including boundary-integral and phase-field methods. The results of theoretical modelling will be compared with results of measurements of the solidification front dynamics and the micro structure evolution from undercooled melts of binary Co-Cu and Cu-Fe alloys, which show a metastable two-phase region in the undercooled melt.