The density of gold-silver-copper alloys and its calculation from the chemical composition

On the assumption that the contribution of a component metal to the density of an alloy is linearly related to the density and concentration of this metal in the alloy it is possible to calculate the values for the density of the system as a whole. Deviation from this behaviour occurs in the alloys formed by the metals of the copper group, and this is significant in the study of gold coins. Although the pure elements gold, silver and copper and their binary and ternary alloys crystallize mainly in the cubic face-centred form, the densities of these alloys do not display a linear correlation with the chemical composition (at%). This is due mainly to the effects of ordering and disordering in the alloys as is described in this paper.