Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti-6Al-4V and Al-4Cu-1Mg

Ultrasonic-assisted brazing of Al-4Cu-1Mg and Ti-6Al-4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti-6Al-4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti-6Al-4V samples and the filler metal. The results show that the TiAl3 phase was formed in the interface between the Ti-6Al-4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti-6Al-4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl3 phase. For the Zn-based filler metal with Si, the TiAl3 phase disappeared and a Ti7Al5Si12 phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl3 phase completely changing to a Ti7Al5Si12 phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138 MPa was obtained from the brazed joint free of the block-like TiAl3 phase. (C) 2011 Elsevier B.V. All rights reserved.