强动力学过冷对类金属聚合物模型合金共晶生长作用机制研究

界面动力学反映相变时界面处原子或分子附着的方式和能力，对共晶生长机制起重要作用。金属体系的动力学效应小，通常在深过冷条件下才能显现，而深过冷状态下一方面无法精确测量界面处的过冷度和生长速度，另一方面不能获取动力学过冷数据，因此难以定量揭示动力学效应对共晶生长的作用机制。类金属聚合物模型合金由于扩散系数小，在生长速度很低时就能获得强的动力学过冷，所以为定量研究强动力学效应提供了可能。但已有研究主要集中在聚合物模型合金等温过冷时的形貌及结晶分数研究方面，难以说明动力学效应的作用机理，所以亟待深入研究。本项目拟选取PEG基类金属聚合物共晶模型合金，采用原位观测定向凝固技术，实现低速生长下的强动力学效应，测量界面处过冷度及共晶相间距，定量获取界面动力学过冷度数据，阐明强动力学效应对聚合物共晶生长的作用规律，并将其与金属共晶体系中的动力学作用相比较，为揭示动力学效应对共晶生长的作用机制提供理论依据。

Interface kinetics reflects the attachment manner and ability of atoms or molecules to the interface, which plays a key role in the growth kinetic process in eutectic growth. The kinetic effect in metallic system is weak, and it usually becomes stronger under high undercooling condition. When undercooling is high, on one hand, the interface temperature and growth velocity are hard to measure; on the other hand, the part of kinetic undercooling cannot be determined quantitatively. This makes the quantitative description on interface kinetics is difficult. Metallic-like polymeric model alloys have small diffusion coefficient, in which strong interface kinetics can be obtained even though the growth velocity is quite low, leading to a possible way to quantitative investigation on interface kinetics. In the literatures, however, most studies on polymeric model alloys focused on the growth morphology and fraction of crystalline fraction under the isothermal condition. In the present project, several PEG based polymeric model eutectic alloys will be used to solidify by using the directional solidification technique combining in-situ observation method. The undercooling and eutectic lamellar spacing will be measured and the kinetic undercooling at interface will be determined, by which the contribution of the strong kinetic effect in polymeric eutectic could be clarified. Moreover, this kinetic effect will be compared with that in metallic eutectic systems. The results of this project will provide an in-depth insight into the effect of interface kinetics on eutectic growth.