Vacuum brazing of TiAl-based intermetallics with Ti-Zr-Cu-Ni-Co amorphous alloy as filler metal

An amorphous Ti41.7-Zr26.7-Cul4.7-Ni13.8-Co3.1 (wt%) ribbon fabricated by melt spinning was used as filler to vacuum braze Ti-48Al-2Nb-2Cr (at%) intermetallics. The influences of brazing temperature and time on the microstructure and strength of the joints were investigated. It is found that intermetallic phases of Ti3Al and gamma-Ti2Cu/Ti2Ni form in the brazed joints. The tensile strength of the joint first increases and then decreases with the increase of the brazing temperature in the range of 900-1050 degrees C and the brazing time varying from 3 to 15 min. The maximum tensile strength at room temperature is 316 MPa when the joint is brazed at 950 degrees C for 5 min. Cleavage facets are widely observed on all of the fracture surfaces of the brazed joints. The fracture path varies with the brazing condition and cracks prefer to initiate at locations with relatively high content of gamma-Ti2Cu/Ti2Ni phases and propagate through them. (C) 2014 Elsevier Ltd. All rights reserved.