Microstructures and mechanical properties of TC4/AZ91D bimetal prepared by solid–liquid compound casting combined with Zn/Al composite interlayer

Abstract

To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface, Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid–liquid compound casting, respectively. Al interlayer was prepared on the surface of TC4 alloy by hot dipping, and Zn/Al composite interlayer was prepared by electroplating process. The results suggested that the phases across the interface were AlTi and α(Al) + Mg21(Al, Zn)17 when Zn/Al composite interlayer was used. When Al interlayer was used as interlayer, AlMgTi ternary structure and Al12Mg17 + δ-Mg eutectic structure were the main phases at the interface. The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer, and the value of the shear strength was increased from 48.5 to 67.4 MPa. Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.