复合场铸造ODS钢外加纳米粒子弥散调控及强化机制研究

Oxide dispersion-strengthened (ODS) steel is the core structure material in a nuclear reactor. Its mechanical properties, corrosion resistance and resistance to neutron irradiation significantly surpass traditional steel. In comparison to conventional powder metallurgy, the cost of production will be dramatically decreased by ODS steel casting. Studies have shown that the implementation of electromagnetic vibration has the potential to cause cavitations in a metal melt, consequently, to solve the agglomeration and clustering of nanoparticles. The project aims to solve above problems using the complex fields (electromagnetic stirring and electromagnetic vibration) in the casting process of ODS steel, instead of the conventional powder metallurgy route. The key is if the capability of electromagnetic vibration is strong enough to result in electromagnetically induced pressure waves in a metal melt which is the origin of the cavitations. Based on the experiments and numerical simulations, this project aims at investigating the interaction mechanisms among nanoparticles, and between nanoparticles and melt, discovering the mechanism of nano-sized Ti-Y-O precipitation during the solidification process, finally to providing theoretical guidance and technical support for casting ODS steel.

氧化物弥散强化钢（ODS钢）是聚变堆的核心结构材料，其机械性能、耐腐蚀特性和抗辐照性能明显优于传统钢种。粉末冶金法是ODS钢的传统制造方法，但成本极高。如果能实现铸造法制备该材料，将极大降低成本。研究表明，冶金熔体中施加超声波或电磁振动会引起空穴现象，可避免纳米粒子在熔体弥散中的团聚。本项目拟在铸造法生产ODS钢过程中利用复合场（电磁搅拌和电磁振动复合场）解决铸造法生产ODS钢中纳米粒子的弥散和团聚问题，从而替代当前的粉末冶金方法。本项目的关键问题是如何使电磁振动设备提供足够强的交变电磁力，从而产生电磁感应的压力波生成空穴对纳米粒子弥散控制。项目旨在通过物理实验和建立纳米粒子运动数学模型，研究纳米粒子与熔体的作用以及相互作用机理，揭示熔体凝固过程中纳米尺寸Ti-Y-O析出相的作用机制，以期为实现铸造法生产ODS钢提供理论指导。

本课题主要研究内容是在铸造法生产ODS钢的过程中利用复合场（电磁搅拌和电磁振荡复合场）解决纳米粒子的弥散和团聚问题，既利用电磁振荡产生的空化效应避免纳米粒子团聚，复合场产生的强化流动对纳米粒子进行全局弥散调控，从而替代当前的粉末冶金方法。阐释电磁振荡下空化形成的机制，明确复合场下空化对流场的影响规律。系统研究了复合场下对合金凝固组织及偏析的影响的基础上，进一步利用复合磁场研究了纳米粒子在合金中的弥散。综合上述研究，明确了电磁振荡下空化形成的机制，确定了复合场纳米粒子弥散调控技术路线。本项目为期四年，共发表SCI论文1篇，授权实验新型专利一项，培养研究生4人。