Effects of chromium and copper additions on precipitation in Al−Zn−Mg alloys

摘要: The effects of chromium and copper additions on precipitation in several Al−Zn−Mg alloys have been investigated. Results show that heterogenize aged by creating special nucleation sites. Multirowed bands incoherent precipitates appeared the grain boundaries subboundaries an Al-5 pct Zn-2 Mg-0.1 Cr alloy. It is believed fine nuclei associated with existence chromium-rich regions are formed during solidification retained after solution heat treatment. These would lead to formation quenching aging. Chromium is, therefore, considered causehigh temperature nucleation. Copper accelerate at lower aging temperatures increase density G. P. zones nucleated relatively (20 90°C). In this way considerably strengthens alloys. Copper, contrast chromium, causes increased low-temperature zones.