Effects of Cu, Mg, Mn, Si and Zn on age hardening of chill cast Al-1%Zr alloy

Abstract

It was reported in a previous paper that supersaturated solid solutions containing up to 1.2% of zirconium in aluminum was obtained by quenching of molten alloys and a remarkable hardening was found after ageing the alloy at 400°C. This paper reports the effects of the third additional elements such as copper, magnesium, manganese, silicon and zinc on the age hardening of Al-1%Zr alloy. The effects were investigated on the wedgeshaped specimens obtained by rapid solidification.The results obtained were as follows:(1) The supersaturated solid solutions containing Zr were found in the thinner part of the wedge-shaped specimens which had been rapidly solidified. The range of thickness of specimens for forming such a structure depended upon the kind and quantity of the third additional elements.(2) Remarkable age hardening was found in the part of the supersaturated structure of the binary Al-1%Zr alloys by ageing at 400°C for 1 hr. The effects of the third elements on the age hardening were arranged in ascending order as follows: Zn<Mg<Cu<Mn (in which the effect of Zn was nearly in the same order as the binary alloy containing no third elements)(3) The alloy containing Si of up to 2% showed remarkable age hardening, but when Si content was more than 2%, the hardening turned to be less.