Microstructure and properties of Al/Cu bimetal in liquid-solid compound casting process

A Ni-P coating was deposited on Cu substrate by electroless plating and the Al/Cu bimetal was produced by solid-liquid compound casting technology. The microstructure, mechanical properties and conductivity of Al/Cu joints with different process parameters (bonding temperature and preheating time) were investigated. The results showed that intermetallics formed at the interface and the thickness and variety increased with the increase of bonding temperature and preheating time. The Ni-P interlayer functioned as a diffusion barrier and protective film which effectively reduced the formation of intermetallics. The shear strength and conductivity of Al/Cu bimetal were reduced by increasing the thickness of intermetallics. In particular, the detrimental effect of Al2Cu phase was more obvious compared with the others. The sample preheated at 780 °C for 150 s exhibited the maximum shear strength and conductivity of 49.8 MPa and 5.29×105 S/cm, respectively.