The Effect of a Zinc Interlayer on the Microstructure and Mechanical Properties of a Magnesium Alloy (AZ31)–Aluminum Alloy (6060) Joint Produced by Liquid–Solid Compound Casting

Abstract

Bimetallic AZ31/6060 joints were produced by compound casting. The process involved pouring liquid magnesium alloy onto a solid aluminum alloy insert placed in a mold. Inserts with and without a zinc surface layer were used. For an insert with no Zn layer, the bonding zone was characterized by a non-homogeneous microstructure. In the area adjacent to the AZ31, there was a eutectic (γ and α(Mg)). In the area close to the 6060 alloy, two continuous layers of the γ and β phases were detected. When a 6060 insert with a Zn layer was used, the bonding zone was mainly composed of Mg-Al-Zn phases. The joint without a Zn interlayer had low shear strength (5.5–11.3 MPa). The presence of the Zn interlayer caused a significant increase in the joint strength (39.8–46.6 MPa). The micro-indentation data suggest a less brittle fracture character of the bonding zone with a Zn layer.