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

Infrared-brazing Fe3Al with Au-44Cu as filler metal has been investigated. The brazed joint consists mainly of a β-phase, Au8-xCu4+xAl4, caused by the dissolution of Al from Fe3Al substrate into the braze alloy. The depletion of Al from Fe3Al 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. Au- 44Cu filler demonstrates a great potential for bonding Fe3Al intermetallic compound. [ABSTRACT FROM AUTHOR]