Structural Analysis of the Interface of Contact Melting between AMg6 and Zn-Based Alloys

We study the processes of the contact melting of AMg6 alloy with a solid Zn–Cu–Al solder and a model Zn–Al alloy, as well as the structure of the contact-melting zone. Sample preparation is carried out in two stages. In the first stage, the solder is mechanically applied (tinned) to the surface of AMg6 plates, and in the second stage, the obtained composite samples are subjected to heat treatment, varying the holding time in the liquid state. According to metallographic analysis, X-ray structural analysis, and differential scanning calorimetry, active interaction between Zn and Al occurs already at the tinning stage, leading to the formation of a developed morphology in the joint area. The presence of copper in the HTS-2000 solder decreases the melting temperature of the Zn–Al alloy by 30–40°C and improves the conditions of contact interaction with the AMg6 matrix. Active zinc diffusion ensures the formation of an extensive melting zone during heat treatment. Regions rich in zinc, upon crystallization, contain the intermetallic phase Zn₅Cu, which hinders the formation of intermetallics based on the ZnMg system, preventing embrittlement of the contact zone.