Microstructural Evolution of Cold-Deformed and Isothermally Treated ZA27 Alloys

Abstract

Pure ZA27 alloys and ZA27 alloys with Cu and Mg additions were cast and deformed by compression. Samples of both alloys were heat treated at 460°C after deformation and the evolution of the microstructure as a function of time measured. The results showed that the average grain size increases with the increase of time for both alloys, with a coarsening rate which is 55% lower for the alloyed ZA27 alloy than the rate of the pure ZA27 alloy. X-ray diffraction analysis indicated that the ZA27 alloys containing Cu and Mg additions present the å phase which is not present in the non-alloyed ZA27 alloy; and that the á and ç phases transform to the â phase during heat treatment. Microhardness measurements showed that the ZA27 alloy with Cu and Mg additions has higher microhardness than the pure ZA27 alloy.