复合活性钎料钎焊Cu与Al2O3的接头组织及性能

为改善紫铜与Al2O3陶瓷的连接强度，采用纳米-Al2O3增强的AgCuTi复合钎料(AgCuTip)对紫铜与Al2O3陶瓷进行了真空钎焊.采用扫描电镜、能谱分析以及剪切试验对钎焊接头微观组织及力学性能进行了分析.钎焊接头典型界面组织为紫铜/扩散层/铜基固溶体+银基固溶体+ Ti2Cu + Ti3(Cu, Al)3O/Al2O3.纳米-Al2O3的添加抑制了Al2O3侧反应层的生长，并促进钎缝中形成弥散分布的Ti2Cu相.随着保温时间的延长，铜侧扩散层和Ti3(Cu, Al)3O反应层的厚度逐渐增大.保温时间为20 min时，铜母材向钎料过度溶解，降低了接头性能.当钎焊温度为880 °C，保温10 min时，接头抗剪强度最高为82 MPa.纳米颗粒的加入细化了钎缝组织并降低了母材与钎缝热膨胀系数的不匹配，因此提高了接头的连接性能.保温时间可影响界面组织及反应层的厚度，进而影响接头的连接强度.
In order to improve the strength of Cu/Al2O3 joint, vacuum brazing of copper to Al2O3 ceramic was performed using nano -Al2O3 strengthened AgCuTi composite filler (abbreviated as AgCuTip filler). The microstructure and mechanical performance of the brazed joint were investigated by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and shear strength test. Typical interfacial microstructure of Cu/AgCuTip/Al2O3 brazed joint is Cu/diffusion layer/Cu-based solid solution + Ag-based solid solution +Ti2Cu +Ti3(Cu, Al)3O/Al2O3. The addition of nano-Al2O3 can improve the interfacial microstructure by inhibiting the growth of reaction layer near Al2O3 ceramic side, and promoting the formation of dispersed Ti2Cu phase in brazing seam. Moreover, both thickness of diffusion layer and Ti3(Cu, Al)3O reaction layer thickened with an increasing holding time. Excessive dissolution of copper was occurred when holding time reached 20 min, which deteriorated the performance of the brazed joint. The highest shear strength of 82 MPa can be obtained when brazed at 880 °C for 10 min. The addition of nano-Al2O3 particles can refine the microstructure of brazing seam and decrease the mismatch of coefficient of thermal expansion between substrates and brazing seam. Therefore, the performance of brazed joint can be improved. The holding time can affect the microstructure and thickness of reaction layer, thereby affect the strength of brazed joints.