AbstractThe effects of the addition of rare earth metals on the electrical conductivity and mechanical properties of commercial purity aluminium have been investigated both in the laboratory and in industrial trials. The electrical conductivity of commercial purity aluminium is increased by about 1% on the international annealed copper standard by the addition of lanthanum, and both its tensile strength and elongation are improved considerably by the addition of cerium. Investigation of the microstructure of the alloys containing rare earth metals shows that the apparent improvement in the electrical conductivity of commercial purity aluminium is caused by a decrease in the solid solubility of impurities in the aluminium.MST/2032