Effect of aging on microstructure and mechanical properties of ZnAl15Cu1 alloy for wrought applications

Abstract

This study investigates the aging behavior of the recently developed ZnAl15Cu1 alloy and its change of mechanical properties with time. Samples obtained from drawn bars were artificially aged at 80 and 220°C for up to several weeks. The mechanical properties were monitored periodically by hardness testing, until a plateau was reached. The microstructural evolution was studied by optical and scanning electron microscope analyses. Bidimensional X-ray diffraction, transmission electron microscopy and selected area electron diffraction experiments were carried out to study the recrystallization phenomena. Nanoindentation measurements were also performed to determine the hardness of the single constituents. It was demonstrated that the aging causes a drop of about 30% in hardness with time. This reduction was related to the recrystallization of the Zn-rich phase network, occurring at both the studied temperatures.