W/ODS–Cuブレージング界面における接合拡散影響部の三次元組織解析

抄録

The oxide dispersion strengthened (ODS)–Cu alloys are expected to be applied as divertor materials for fusion reactors by brazing with tungsten due to their high thermal conductivity, microstructural stability at high temperatures, and irradiation resistance properties. On the other hand, the interfacial microstructure affects its mechanical and functional properties, which is important to analyze in fusion reactor applications. In this study, we fabricated a brazed bonding interface, which is one of the potential bonding methods between ODS–Cu and tungsten, and analyzed the three–dimensional microstructure of the interface. Consequently, the diffusion of nickel atoms, the raw material of the brazing material, obtained two characteristic microstructures： first, in the nickel atoms diffusion region, nickel was solidly dissolved by copper and enhanced the grain growth of copper while remaining in a dispersed oxide distribution. In the other, nickel formed an intermetallic compound NiW₂ with tungsten and was distributed to cover the bonding interface. The formation of NiW₂ is predicted to cause a decrease in thermal conductivity, while suggesting that it may increase the strength of the brazing interface.