Determination of key parameters of nucleation from optical investigations of mesoscopic models

该项目旨在确定成核的关键参数（界面张力，动力学前因子，熔体结构和过冷度）在单组分和二元胶体剪切熔体的系统。这些系统高度类似于原子系统，特别是金属系统，但相比之下，通过光学技术如显微镜，光和小角度X射线散射显示出方便的可达性。基于第一个资助期的工作，其中相行为，熔体结构和成核动力学研究了一些选定的系统，我们现在希望将成功测试的技术应用于显示bcc/fcc相边界，化合物形成和/或共晶特征的分散体。所有这些特征在金属中都很常见。我们的界面能的结果应该是直接可比的金属（特别是富铁合金），但也明确占熔体结构，我们从USAXS测量模型。预因子将根据“过冷度”进行研究，使用测量的均匀速率密度的阿克里尼乌斯评估。这将允许讨论集体动力学在成核过程中的可能参与。

This project aims at the determination of the key parameters of nucleation (interfacial tension, kinetic prefactors, melt structure and undercooling) in systems of single component and binary colloidal shear melts. These systems are highly analogous to atomic and in particular metallic systems, but by contrast, display a convenient accessibility via optical techniques like microscopy, light and small angle x-ray scattering. Based on the work of the first funding period, where the phase behaviour, the melt structure and the nucleation kinetics were studied for a number of selected systems, we now want to apply the successfully tested techniques to dispersions showing bcc/fcc phase boundaries, compound formation and/or eutectic features. All these features are common in metals. Our results for interfacial energies should be directly comparable to those obtained in metals (in particular for Fe-rich alloys), but also to models accounting explicitly for the melt structure which we obtain from USAXS measurements. Pre-factors will be investigated in dependence on “undercooling” using an Arrhenius evaluation of measured homogeneous rate densities. This will allow to discuss the possible involvement of collective dynamics in the nucleation process.