Interfacial bonding mechanism and mechanical properties of novel AZ31/WE43 bimetal composites fabricated by insert molding method

AZ31/WE43 bimetal composites are prepared by insert molding method, and the microstructure evolution, phase constitution and bonding strength at the interface are investigated. A relatively uniform transition interface with a thickness of 50 to 150 μm is formed, indicating a good metallurgical bonding. The analysis shows the transition interface is mainly composed of lamellar-like and particulate Al2RE phase, particulate Al3Zr phase on AZ31 side, a precipitation free zone (PFZ) in the middle and quadrate-like Y-rich phases congregated together at the grain boundary close to WE43 side. The average interface shear strength is 108 MPa, which is much superior to other bimetal composites reported so far. The fracture analysis indicates that during the shear tests, the cracks initiates from the weak zone of casting AZ31 alloy. Aided by the interface microstructure, the mechanism on interface bonding is further discussed.