Effect of annealing on the microstructure and mechanical properties of Al/Zn composite plates

The study examined how various annealing methods affect the structure and characteristics of Al/Zn layered composite plates. Four distinct composite plates underwent annealing at temperatures of 160 °C, 200 °C, and 240 °C for durations ranging from 0.5 h, 1 h, 1.5 h, and 2 h. Changes in grain structure, interface appearance, and thickness of the interface diffusion layer were analyzed using metallographic microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Tensile and microhardness tests were performed under different annealing conditions and cycling durations. Results showed that as annealing time increased, tensile strength initially rose before declining, while elongation remained consistently high. The optimal balance between strength and ductility was observed at 200 °C for 1.5 h of annealing across all plate types. Before annealing, Al displayed a fractured ultrafine crystalline structure, while Zn's texture underwent changes.