拉伸断口较为平整，这也表明界面区的钎料和母材实现良好冶金结合。断口微观形貌如b图所示，形貌为韧窝形貌，说明接头为韧性断裂。其中韧窝形貌有大而深的韧窝和小而浅的韧窝。试样拉伸过程中焊缝受应力较大部位形成大而深韧窝，受应力较小部位形成小而浅韧窝。对断口中小而浅的韧窝进行能谱分析，发现成分与d点相近，Ag元素含量高于3点，且有钎剂F、K元素残留，可以推测钎焊接头起裂源为富Cu相与富Ag相界面，起裂后裂纹沿着富Ag相扩展。

The tensile fracture is relatively flat, which also indicates that the brazing filler metal and the base metal in the interface zone have achieved good metallurgical bonding. The microscopic morphology of the fracture is shown in Figure b, and the morphology is a dimple morphology, indicating that the joint is ductile fracture. Among them, the morphology of dimples has large and deep dimples and small and shallow dimples. During the tensile process of the specimen, large and deep dimples are formed in the more stressed parts of the weld, and small and shallow dimples are formed in the less stressed parts. The energy spectrum analysis of the small and shallow dimples in the fracture shows that the composition is similar to the point d, the content of Ag is higher than 3 points, and there are residual fluxes F and K. It can be inferred that the origin of the brazing joint is the Cu-rich phase. At the interface with the Ag-rich phase, the crack propagates along the Ag-rich phase after cracking.