Microstructure and mechanical property of transient liquid phase bonded aluminum silicon alloy joint

Microstructure and mechanical property of the transient liquid phase bonded aluminum silicon alloy joints with Cu interlayer were investigated by means of scanning electron microscope, X-ray diffractometry, energy dispersive X-ray spectroscope and electronic tensile testing machine.The results indicate that Cu interlayer reacts with Al from Al-Si alloy to form eutectic liquid phase, and Si from Al-Si alloy will prevent the reaction to some extent.The microstructure of the joint consists of α-Al, Si and intermetallic compounds(CuAl₂ and Al₄Cu₉), meanwhile, the amount of the intermetallic compounds decrease with the increasing of bonding time.The fracture occurs at the bonding region/base metal interface during shear strength testing.With the increase of bonding time, the shear strength of the joint increases firstly and then declines, while 70.2 MPa can be achieved after bonding at 560℃ for 120 min.In addition, a transition from brittle to hybrid brittle and ductile morphology of the fracture surface was found with the increasing of bonding time.