Title: Effect of Thermomechanical Treatment on Work-Softening of Zn-Al Alloys
Abstract: In the present work, the range of chemical composition and the condition of working and heat treatment for work-softening in Zn-Al alloys were examined. Work-hardening in Al-rich alloys and work-softening in Zn-rich alloys were always observed regardless of pre-treatment conditions. Recovery and recrystallization in the work-softened specimens was confirmed by the measurements of micro-Vickers hardness and the observations of optical microstructure. It has been suggested that the cold-working causes the precipitation of dissolved Al which results in the lowering of recrystallization temperature and that the work-softening occurs due to the recovery and recrystallization of worked-specimens at room temperature. In Al-rich alloys, the work-softening was suppressed. This was because the precipitation of Zn was relatively suppressed and remained in the state of the formation of G.P. zones and then the recovery and recrystallization did not proceed.