燃烧合成反应自生复相熔体非平衡凝固行为的同步辐射动态研究

The combination of combustion synthesis and melting technologies provides a novel method to prepare fully dense materials with (ultra-) high melting point in one step. However, due to the difficulty of a dynamic study on combustion and solidification processes, the reaction and solidification mechanisms and the structural evolution mode for the products are not clear.In the present study, an in-situ and real time characterization and visulization with non-equilibrium solidification process of metal-ceramics or intermetallics melts formed during combustion synthesis will be conducted using synchrotron radiation (including X-ray diffraction and X-ray imaging) and levitator facilities. The combustion synthesis reaction is induced by a laser. This study focuses on thermodynamic and kinetic conditions to form melt in reaction system, the formation and selection mechamisms of the intermediate phases,non-equilibrium solidification behavior of multi-constituent and complex-phase melt, and microstucture elvolution of the products. By doing this, one desires to understand the reaction mechanism of the system and the non-equilibrium solidification mechanism of the melt, and kinetic mechanism during microstructure evolution. In addition, the correlation between combustion synthesis and solidification process will be modeled. It is of great importance to analyze the theoretical base and the experimental results in order to control effectively the combustion sytnthesis and the microstucture of the product.

燃烧-凝固复合技术为实现金属-陶瓷/金属间化合物等（超）高熔点材料的合成与同步致密化制备提供了新的有效途径。然而，目前尚缺乏对燃烧反应及非平衡凝固过程开展原位、实时、动态的研究；合成体系的反应、凝固及产物组织演变机制还需探索。本项目通过同步辐射（XRD及实时成像）和悬浮技术相结合，实现燃烧合成中熔体非平衡凝固进程的实时表征和动态可视化。研究激光热源作用下反应体系熔化的热力学与动力学条件，中间亚稳相的形成和选择机制，多元复相熔体的非平衡凝固组织结构演变规律，从而揭示燃烧合成体系的反应机理，燃烧熔体的非平衡凝固机制和产物组织演变动力学机制，弄清燃烧反应与凝固进程的相关性规律，为有效控制燃烧合成过程和优化产物组织结构提供理论基础和技术支撑。

燃烧-凝固复合技术为实现金属-陶瓷/金属间化合物等（超）高熔点材料的合成与同步致密化制备提供了新的有效途径。然而，目前尚缺乏对燃烧反应及非平衡凝固过程开展原位、实时、动态的研究；合成体系的反应、凝固及产物组织演变机制还需探索。本项目通过同步辐射实时成像技术，实现燃烧合成中熔体非平衡凝固进程的实时表征和动态可视化。研究了复相体系不同溶解度下界面反应过程中金属间化合物形成次序、生长行为与长大机制，与非平衡凝固过程中不同金属间化合物的生长动力学，揭示了反应条件及溶解度对界面组织演变影响规律；分析了复相体系界面反应过程中金属间化合物的异向生长行为、长大机制、溶解行为、择优取向及非平衡凝固过程中不同金属间化合物的形貌演变，揭示溶解对金属间化合物的加速生长机制及不同形貌金属间化合物演变规律；研究了反应体系中氢气泡的个体与群体生长行为及金属间化合物与气泡的相互作用生长行为，探讨了个体气泡生长及群体气泡合并机制、界面及熔体中气泡与金属间化合物的交互作用机制。