Mechanical and thermal properties of the Al-Zn-Mg-Cu alloy with/without Sc,Zr-addition in the cast state and cold-rolled state (with reduction of 6% and 21%) were investigated. The distinct changes in microhardness curves and heat flow are caused by formation of the clusters/Guiner-Preston zones and subsequent precipitation of the metastable eta'-phase particles.
Positive effect of the Sc,Zr-addition on hardening is observed at annealing temperatures above 330 °C.