C/C复合材料与Invar合金钎焊接头组织性能研究

Microstructure and mechanical properties of C/C composite/Invar alloy joints brazed with Cu-Sn-Ti alloy

摘要:

C/C复合材料是一种重要的航空航天和核结构材料，实现其与金属材料的连接可以克服其成本高和成型加工困难的问题。本文采用Cu-Sn-Ti活性钎料钎焊C/C复合材料与Invar合金，研究了钎焊温度和保温时间对接头组织、剪切强度和断裂行为的影响。结果表明，在C/C复合材料一侧，Cu-Sn-Ti与C/C形成TiC反应层并实现连接，同时Cu-Sn-Ti会渗透进C/C复合材料中，形成凹凸不平的钉扎界面并强化接头；在Invar合金一侧，Cu-Sn-Ti与其相互溶解扩散并发生反应，形成良好界面结合；钎焊接头组织结构为Invar合金/Cu(s,s)+Fe2Ti+Ni3Ti+Ti6Sn5/Fe2Ti+CuTi+Cu3Sn/TiC+Cu(s,s)/C/C复合材料。在钎焊温度为930 ℃保温10 min时，接头剪切强度最高，为61 MPa，明显高于目前报道的C/C复合材料与金属的钎焊连接强度。

关键词:C/C复合材料;Invar合金;钎焊;微观组织;剪切强度

Abstract:

C/C composites are the important structure materials for aerospace and nuclear applications. Realizing the joining of C/C composite to metal materials can overcome the drawbacks of high cost and hard-to-forming difficulties of C/C composite. In this paper, C/C composite and Invar alloy were brazed with active Cu-Sn-Ti filler alloy. The effects of brazing temperature and holding time on the microstructure, shear strength and fracture behavior of brazed joints were investigated. The results showed that, on the side of C/C composite, Cu-Sn-Ti filler reacted with C/C composite to form a TiC reaction layer. In addition, Cu-Sn-Ti filler would penetrate into the C/C composite, which formed a zigzag interface that strengthened the joint. On the side of Invar alloy, Invar alloy dissolved into Cu-Sn-Ti form a good interface metallurgical bonding. The interfacial microstructure of brazed joint was determined to be Invar alloy/Cu(s,s)+Fe2Ti+Ni3Ti+Ti6Sn5/Fe2Ti+CuTi+Cu3Sn/TiC+Cu(s,s)/C/C composite. The maximum shear strength of the joint of 61 MPa, which is significantly higher than the strength reported in previous studies, was obtained at brazing temperature of 930 ℃ and the holding time was 10 min.

Key words:C/C composite; Invar alloy; brazing; microstructure; shear strength