Interfacial Structure and Properties of Al2O3 Ceramic and TiAl Alloy Brazed Joints

Abstract:

Al2O3 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. Results show that the typical interfacial microstructure of the brazed joints was: Al2O3/Ti3(Cu,Al)3O/Ag(s.s)+Cu(s.s)+AlCu2Ti/AlCuTi/TiAl. During the brazing, Ti and Al would dissolve from the TiAl substrate and make a major impact on the microstructure and mechanical properties of the brazed joints. With the increase of brazing temperature and time, the thickness of Ti3(Cu,Al)3O reaction layer increased and the blocky AlCu2Ti compounds aggregated and grew up gradually, which influced collectively the mechanical properties of the jont. The average shear strength reached a maximum of 94 MPa with the joint brazed with 880 ℃/10 min. The crack primarily propagated at Al2O3 substrate and partially along the reaction layer.

Key words:TiAl alloy; Al2O3 ceramic; brazing; interfacial microstructure; shear strength