基于纳米量热技术的界面诱发金属微滴形核机制研究

凝固是材料尤其是金属材料制备的重要手段，凝固过程包括形核与其后的晶体生长过程。对凝固过程的形核进行调控，对于金属材料的组织细化和性能提升具有至关重要的作用。现有研究发现，经典的异质形核界面适配度理论并不能完全解释异质形核的形成过程。因此，金属凝固过程异质形核的界面诱发效应及其内在的作用机制仍旧是值得深入研究的科学命题。本项目拟采用真空蒸镀、磁控溅射和晶面切割等手段结合，设计具有不同成分、组织及晶体结构与取向的形核界面，并利用纳米量热仪所具有的大范围加热-冷却速率（1～1000000℃/s）、高灵敏度（<1nJ/℃）及极高真空度（高于E-6Pa）的独特优势，通过精确控制单个微米尺度金属微滴的过冷状态，系统研究成分、组织、晶体结构及晶面取向等界面特征条件下界面诱发异质形核的行为及其内在机制。该研究有望为金属凝固形核理论的研究开辟一条新的途径，并为金属凝固理论的丰富和发展提供创新性成果。

Solidification is one of the crucial techniques to fabricate materials, especially for the metallic materials. The solidification process includes the nucleation and crystal growth. In addition, it is really significant for the microstructure refinement and property improvement by controlling the nucleation process. Unfortunately, the popular classical lattice fit theory of the heterogeneous nucleation does not always work. Therefore, it still remains a scientific issue to investigate the interface-induced effect and its inherent mechanism for the heterogeneous nucleation during the solidification process. In this project, the interfaces with various composition, microstructure and crystal lattice/orientation will be designed by combining the vacuum evaporation, magnetron sputtering and crystal face cutting etc., by which to induce the heterogeneous nucleation. Meanwhile, the undercooling can be precisely controlled by the nanocalorimeter, which possesses the advantages such as large heating-cooling rate (1～1000000℃/s), high sensitivity (<1nJ/℃) and extreme vacuum (about E-6Pa) etc. As a result, the regularity and inherent mechanism of the interface-induced heterogeneous nucleation can be systematically discussed. This project is anticipated to open a novel approach to investigate the solidification nucleation, and offer innovative results for the enrichment and development of the metal solidification theory.