DU Zhongjie, LI Dan, ZHANG Yuxin, XIAO Yong
(School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, Hubei, China)
Abstract: Cu-Ti composite solder was used to braze Si3N4/Cu joints at different temperatures for different holding time durations, focusing on the effects of brazing parameters on their microstructure and mechanical properties. It is found that the main phases include TiN, Ti5Si3 and Cu-Ti. At low temperatures (890 ℃), Ti5Si3 was formed first. Due to the low reaction extent, less Ti diffused into Cu, resulting in the formation of Cu3Ti. With prolonged holding time or elevation to higher temperatures (920 ℃), TiN was formed as a thin layer at the interfaces. More Ti diffused into Cu, leading to the transformation of Cu3Ti into CuTi. Simultaneously, Ti5Si3 also diffused into Cu to a certain degree. At excessively high brazing temperatures (950 ℃), there was a significant reaction between Ti and Si3N4, leading to the consumption of Cu-Ti compounds as intermediate phases. Consequently, the peel strength showed an initial increase, followed by a decrease with increasing temperature. In the joint brazed at 920 ℃ for 60 min, TiN gradually peeled off in thin layers, further optimizing the interface structure. The peel strength of the joint reached highest value of 16.69 N·mm−1.
Key words: active metal brazing; silicon nitride; copper-titanium solder; ceramic copper clad laminate; AMB