Direct diffusion bonding of immiscible tungsten and copper at temperature close to Copper's melting point

• Published in: Materials & design Vol. 137; pp. 473 - 480
• Main Authors: Zhang, Jie, Huang, Yuan, Liu, Yongchang, Wang, Zumin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 05.01.2018
• Subjects: Direct diffusion bonding; Melting point of copper; Metallurgical interface; W–Cu immiscible system; Melting point of copper; W–Cu immiscible system; Direct diffusion bonding; Metallurgical interface
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2017.10.052

•Direct diffusion bonding method is a feasible way to construct a metallurgical bonding interface between immiscible W and Cu.•The key point of the direct diffusion bonding is that bonding temperatures should be close to copper's melting point.•The maximum tensile and bending strengths of the obtained W/Cu joints are about 172MPa and 232MPa, respectively.•A diffusion occurs between W and Cu and the thickness of the W/Cu diffusion layer is about 22nm. [Display omitted] In this study, a direct diffusion bonding method is designed to bond tungsten (W) and copper (Cu) without using an interlayer metal at a temperature close to the melting point of copper (TmCu). The results show that the direct diffusion bonding method is feasible and the key point to a successful connection is that bonding temperatures should be controlled in an effective temperature range 0.81TmCu–0.97TmCu. The most appropriate bonding parameters are that the bonding temperature is 980°C, the bonding time is 180min and the bonding pressure is 106MPa. The maximum tensile and bending strengths of the as-obtained W/Cu joints are ~172 and ~232MPa, respectively, which reach a very high level compared to pure copper. The corresponding fractures are ductile. The micro-tests for the W/Cu joint show that diffusion occurs between W and Cu and the thickness of the W/Cu diffusion layer is ~22nm. Through the diffusion, a metallurgical bonding interface has been successfully constructed, which is the essential reason for the high strengths of the W/Cu joint. The diffusion between W and Cu when the bonding temperature is close to TmCu may be induced by the high-temperature structure of Cu, which needs further investigation.