Al_2O_3陶瓷与TiAl合金真空钎焊接头界面组织及性能

Interfacial Structure and Properties of Al_2O_3 Ceramic and TiAl Alloy Brazed Joints

采用AgCuTi活性钎料实现了Al_2O_3陶瓷与TiAl合金的钎焊连接,研究了钎焊接头的界面结构及其形成机制,并且分析了不同钎焊参数对接头界面组织和接头力学性能的影响规律。结果表明:Al_2O_3陶瓷与TiAl合金钎焊接头的典型界面组织为:Al_2O_3/Ti_3(Cu,Al)_3O/Ag(s.s)+Cu(s.s)+AlCu_2Ti/AlCu_2Ti+AlCuTi/TiAl。钎焊过程中,TiAl基体向液态钎料中的溶解量决定了钎焊接头界面组织的形成及其演化。随着钎焊温度的升高和保温时间的延长,Al_2O_3陶瓷侧的Ti_3(Cu,Al)_3O反应层增厚,钎缝中弥散分布的团块状AlCu_2Ti化合物逐渐聚集长大。陶瓷侧界面反应层的厚度和钎缝中AlCu_2Ti化合物的形态及分布共同决定着接头的抗剪强度。当钎焊温度为880℃,保温10 min时,接头的抗剪强度最大,达到94 MPa,此时接头的断裂形式呈现沿Al_2O_3陶瓷基体和界面反应层的复合断裂模式。

Al_2O_3 ceramic and TiAl alloy were brazed with AgCuTi filler and the interfacial structure with the change of brazing parameters as well as the forming mechanism of the joint were studied.The results show that the typical interfacial microstructure of the brazed joints is Al_2O_3/Ti_3（Cu,Al）_3O/Ag（s.s）＋Cu（s.s）＋AlCu_2Ti/AlCu_2Ti＋AlCuTi/TiAl.During the brazing,Ti and Al can dissolve from the TiAl substrate and make a major impact on the microstructure and mechanical properties of the brazed joints.With increasing of brazing temperature and time,the thickness of Ti_3（Cu,Al）_3O reaction layer increases and the blocky AlCu_2Ti compounds aggregate and grow up gradually,which influences collectively the mechanical properties of the joint.The average shear strength reaches a maximum of 94 MPa with the joint brazed with 880°C/10 min.The crack primarily propagates at Al_2O_3 substrate and partially along the reaction layer.