Infrared brazing of Fe3Al intermetallic compound using gold-based braze alloy

Abstract

Infrared-brazing Fe 3 Al with Au-44Cu as filler metal has been investigated. The brazed joint consists mainly of a β-phase, Au 8 − x Cu 4+ x Al 4 , caused by the dissolution of Al from Fe 3 Al substrate into the braze alloy. The depletion of Al from Fe 3 Al substrate results in the formation of a layer of β-phase particles dispersed in the Fe-rich phase. The highest shear strength for AuCu filler is 327 MPa for specimens infrared brazed at 880°C for 180 s. The brazed joint is mainly fractured along the central β-phase in which the fractograph exhibits quasi-cleavage with dimples. Increasing the brazing time or temperature will deteriorate the bonding strength of the joint, and the fracture mode is prone to cleavage of brittle fracture. Au44Cu filler demonstrates a great potential for bonding Fe 3 Al intermetallic compound.