Effect of holding time on microstructure and mechanical properties of ZrO_2/TiAl joints brazed by Ag-Cu filler metal

摘要

Reliable joining of ZrO_2 ceramic to TiAl alloy is crucial for the success of the engine industrial application. However, there have been few systematic investigations on joining of ZrO_2 ceramic and TiAl alloy. In this study, reliable brazing of ZrO_2 ceramic and TiAl alloy was achieved using inactive AgCu filler metal. The interfacial microstructure of the joints was characterized by SEM, XRD and TEM. Effects of holding time on the microstructure and mechanical properties of the joints were investigated in details. The results revealed that Cu_3Ti_3O + TiO layers were formed adjacent to ZrO_2 ceramic while AlCu_2Ti layer was formed at TiAl substrate. The thickness of Cu_3Ti_3O + TiO layers increased and the granular AlCu_2Ti coarsened gradually with the prolongation of holding time. The hardness and Young's modulus of reaction phases were characterized by nano-indentation to reveal the plastic deformability. The highest shear strength of 48.4 MPa was achieved when brazed at 880 ℃ for 10 min.