C/C复合材料与TC4钎焊接头的组织与断裂形式分析

Microstructure and fracture properties of carbon/carbon composite and TC4 titanium alloy joints

在钎焊时间10min，钎焊温度820～900℃的条件下，采用AgCu钎料对C／C复合材料和TC4进行了钎焊试验。利用扫描电镜、X射线衍射分析仪、EDS能谱分析仪对接头的界面组织及断口形貌进行了研究。结果表明，C／C复合材料与TC4连接接头的界面结构为C／C复合材料／TiC＋C／TiCu／Ag（s．s）＋Cu（s．s）＋Ti3Cu4／Ti3Cu4／TiCu／Ti2Cu／Ti2cu＋Ti（s．s）／TC4。由压剪试验测得的接头抗剪强度可知，在钎焊温度850℃，保温时间10min的钎焊条件下，接头获得的最高抗剪强度达到38MPa。接头的断口分析表明，接头的断裂位置与被连接处碳纤维方向和钎焊温度有关。当碳纤维轴平行于连接面时，断裂发生在复合材料中。当碳纤维轴垂直于连接面时，若钎焊温度较低，断裂发生在C／C复合材料／钎料界面处；若钎焊温度较高，断裂主要发生在C／C复合材料／钎料界面和钎料／TC4界面处。

C/C composites and TC4 titanium alloy were joined using AgCu filler metal at brazing temperature of 820-900 ℃ for 10min.Interface microstructures and fracture surfaces were investigated by scanning electron microscopy,X-ray diffraction and EDS energy spectrum.The results showed the typical interface microstructure of C/C composite and TC4 brazed joints could be expresses as C/C composite/TiC+C/TiCu/Ag(s.s)+Cu(s.s)+Ti3Cu4/Ti3Cu4/TiCu/Ti2Cu/Ti2Cu+Ti(s.s)/TC4.The shear strength of the brazed joints was 38 MPa at 850 ℃ for 10min.The analysis of fracture surface showed that the situation of fracture surface was related to the orientation of carbon fiber and brazing temperature.When carbon fiber was parallel to the joining surface,the joints were fractured in the composites.When carbon fiber was vertical to the joining surface,the joints were mainly fractured in the C/C composite/filler metal interface with low brazing temperature.Meanwhile,the joints were fractured in the C/C composite/filler metal interface and filler metal/TC4 interface with high brazing temperature.