Abstract:The effects of heat treatment on the microstructure and mechanical properties of ZA27 alloy were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical characterization. The results indicated that the as-cast microstructure of the alloy was mainly composed of α, decomposed β, η and ε phases. After solid solution treatment at 365 °C for 1 h, α and η phases dissolved, and the microstructure of specimen was mainly composed of the supersaturated β phases. The phase decomposition of supersaturated ZA27 alloy is a two-stage phase transformation: the decomposition of the supersaturated β phase at the early stage of aging, and with the increase of aging time, ε phase decomposition through a four-phase transformation: α+ε→T ′+ η. A good combination of high tensile elongation and reasonable strength can be achieved by suitable heat treatments.

Key words: ZA27 alloy; heat treatment; solid solution; aging; mechanical properties; microstructure