Effect of Small Amounts of Additional Elements on Aging Characteristics of Al-9at%Mg Alloy

Abstract

Effects of 0.1at% Cr, Zr, Fe, V, Ag, Be, Cd, In, Si, Ge, Sn and 0.01∼0.5 at% Cu on aging characteristics of Al-9at% Mg alloy have been studied by measurements of electrical resistivity and hardness and electron microscope observations.
The rate of clustering in Al-9at% Mg alloy is remarkably decreased by the addition of more than 0.03 at% Cu. In the Cu-bearing alloys two kinds of clusters exist : one is composed of Mg and Al atoms and the other includes Cu atoms. The latter exists even above 100°C, at which the former is easily dissolved.
Transition elements such as Cr, Zr, Fe and V retard slightly the clustering, but accelerate precipitation at higher temperatures.
The effects of Ag, Be, Cd and In on aging kinetics are also similar to the case of those transition elements, except that these elements prevent the formation of precipitate-free zones and produce a finer dispersion of precipitates.
It seems that Si, Ge and Sn have no trace-element effect on the clustering and the precipitation in Al-9at% Mg alloy.