Mechanical properties and microstructure of TiAl/42CrMo joint induction brazed with Ag-Cu-Ni-Li filler metal

Induction brazing of TiAl to 42CrMo steel under the protection of Ar gas was carried out with a Ag-Cu-Ni-Li filler metal. The results show that Ti₃Al, AlCuTi, AlCu₂Ti, Ag-based solid solu-tion, Ag-Cu eutectic and TiC phase occur at the interface of the brazed joint. When the joint was brazed at 1000℃ for 30 s, the in-terface is mainly composed of the Al-Cu-Ti ternary intermetallics; its strength is not very high; crack occurs in the Al-Cu-Ti ternary intermetallics. When it was brazed at 890℃ for 30 s, room temperature and elevated temperature(400℃)tensile strength of the joint is up to 309 MPa and 286 MPa, respectively. Crack occurs initially at the phase boundary of the AlCu₂Ti particles and the Ag-based solid solu-tion, then expands to the reaction layers adjacent to the base metals and results in failure.