Study of ceramic coherent interface produced by solid-liquid reaction

本研究将电阻焊技术应用于碳化硅与金属的连接。用高分辨电子显微镜观察了焊接界面结构，揭示了焊接过程中的反应。此外，为了揭示电阻焊过程中反应产物的形成机理，我们将原位加热HRTEM技术应用于碳化硅/金属熔体反应中。首先，研制了碳化硅与金属之间的电阻焊机。碳化硅的最高结合温度随焊接电流上升速率的变化而变化。在碳化硅/铝体系的焊接界面上，与碳化硅相邻形成了Al_4C_3、Al和非晶相。碳化硅/铝界面在原子水平上是平坦的，观察到了碳化硅与铝之间的晶体取向关系。对于碳化硅/银-铜-钛合金体系，界面处形成了TiC和Ti5Si3两种反应相。反应相厚度随焊接电流上升速率的变化而变化，在特定的焊接条件下，银直接与碳化硅相邻形成，而没有反应相。原位加热HRTEM技术表明，在碳化硅衬底上扩散的银-铜-钛熔体的前端形成了TiC，Ti5Si3形成在TiC的前方约10 nm处。在肌萎缩侧索硬化症的前端没有观察到习惯面。尽管存在较薄的TiC层区，但仍观察到了(10-12)SiC//(111)TiC、[1-210]SiC//[1-10]TiC等晶向关系。相反，在铺展的合金熔体前沿也观察到了TiC的层层生长。

In this study, resistance welding was applied to the bonding of SiC to metals. The welded interface structure was observed by high-resolution transmission electron microscopy to reveal the reaction during welding. In addition, in order to reveal the mechanism of the reaction products formation during resistance welding, we applied in-situ heating HRTEM technique to SiC/molten metals reactions.Firstly, we developed the resistance welding machine to bond the SiC to metals. The maximum bonding temperature of SiC varied with the rate of welding current rise. At the welded interface, A1_4C_3, Al and an amorphous phase were formed adjacent to SiC in the SiC/Al system. The SiC/Al interface was flat at the atomic level and the crystallographic orientation relationship between SiC and Al was observed. For the SiC/Ag-Cu-Ti alloy system, the reaction phases TiC and Ti_5Si_3 were formed at the interface. The thickness of the reaction phases varied with the rate of welding current rise, and, under specific welding conditions, Ag formed directly adjacent to SiC without the reaction phases.The in-situ heating HRTEM technique revealed that, at the front of the spreading Ag-Cu-Ti molten alloy on the SiC substrate, TiC is formed and the Ti_5Si_3 is formed approximately 10 nm behind the front of the TiC. No habit plane is observed at the front of the TiC. In spite of the thin TiC layer region, crystallograp hic orientation relationship is observed between SiC and TiC such as (10-12)SiC//(111)TiC, [1-210]SiC//[1-10]TiC. In contrast, layer by layer growth of TiC at the front of the spreading molten alloy was also observed.