Structural evolution in a continuously cast eutectoid Zn–Al-based alloy

The microstructure and ageing characteristics of a continuously cast eutectoid Zn–Al-based alloy were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) techniques. It was found that the layer microstructure of the continuously cast Zn–Al-based alloy consisted of a decomposed βs′ phase at the surface of the cast ingot, an intermediate region with a cellular structure and the typical dendritic structure in the central part of the ingot. Two stages of phase decomposition were detected during ageing at 170 °C.