Effect of Bonding Temperature on Microstructure and Properties of 5A06 Aluminum Alloy Transient Liquid Phase Diffusion Bonding Joint

Transient liquid phase diffusion bonding of 5A06 aluminum alloy was carried out by using Al-Cu-Si-Ni amorphous foil as the interlayer in argon protection atmosphere with banding time of 10 min and bonding pressure of 2.5 MPa. The influences of bonding temperature (550-590℃) on the microstructure and performance of joints were studied. The results show that the increase of bonding temperature could promote the diffusion of interlayer melting point depressant elements(Cu,Si and Ni), and reduce the formation of brittle phase in weld microstructure, and thus improve the tensile strength of the joint; but the tensile strength of the joint decreased when the bonding temperature was 590℃. The optimum bonding temperature was 580℃ under test conditions; at this point, the diffusion of melting point depressant elements between the interlayer and the base metal was sufficient, and the joint interface was fuzzy, indicating the joint quality was good; the weld center had the smallest hardness of 76.5 HV and the largest tensile strength of 239 MPa, and the fracture mode was ductile fracture.