Li Shengnan, Du Dong, Zhang Lei, Hao Qingle, Long Weimin
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Advanced Brazing Filler Metals & Technology, Zhengzhou Research Institute of Mechanical Engineering Co., LTD, Zhengzhou 450001, China.
Materials (Basel). 2021 Apr 8;14(8):1844. doi: 10.3390/ma14081844.
C/C composite was brazed to TiAl intermetallic compound using a commercial BNi-2 brazing filler metal under vacuum brazing condition. The brazing temperature was 1030~1150 °C and the holding time was 20 min. The joint interfacial microstructures and mechanical properties were studied, and the fracture behavior and joining mechanism were also investigated. The effect of brazing temperature on the joint shear strength was explored. The results showed that a perfect interface joint can be obtained by using BNi-2 to braze C/C and TiAl. During brazing, Ti, Cr, and other carbide forming elements diffused to C/C composite side, forming CrC, CrC, TiC, and other carbides, and realizing metallurgical joining between the brazing filler metal and C/C composite. The microstructure of the interface of C/C composite and TiAl intermetallic compound joint is as follows: TiAl alloy → TiAl + AlNi → AlNiTi → Ni(s, s) + TiAl + NiSi → Ni(s, s) + Ni(Si, B) + CrB → Ni(s, s) + NiSi + TiCr → (Ti, Cr)C → C/C composite. When the holding time is fixed, with the increase of brazing temperature, the shear strength of the joint increases first and then decreases. The maximum average room temperature shear strength of the brazed joint was 11.62 MPa, while the brazing temperature was 1060 °C and the holding time was 20 min.
在真空钎焊条件下，使用商用BNi-2钎料将C/C复合材料钎焊到TiAl金属间化合物上。钎焊温度为1030~1150℃，保温时间为20分钟。研究了接头界面微观结构和力学性能，还研究了断裂行为和连接机制。探讨了钎焊温度对接头剪切强度的影响。结果表明，使用BNi-2钎焊C/C和TiAl可获得完美的界面接头。钎焊过程中，Ti、Cr等碳化物形成元素扩散到C/C复合材料一侧，形成CrC、CrC、TiC等碳化物，实现了钎料与C/C复合材料之间的冶金连接。C/C复合材料与TiAl金属间化合物接头界面的微观结构如下：TiAl合金→TiAl+AlNi→AlNiTi→Ni（固溶体，s）+TiAl+NiSi→Ni（固溶体，s）+Ni（Si，B）+CrB→Ni（固溶体，s）+NiSi+TiCr→（Ti，Cr）C→C/C复合材料。当保温时间固定时，随着钎焊温度的升高，接头的剪切强度先增大后减小。钎焊接头的最大平均室温剪切强度为11.62MPa，此时钎焊温度为1060℃，保温时间为20分钟。
