An aluminum alloy comprising Al, Sc, Gd, Zr, and optionally Mg. The aluminum alloy is strengthened by an aluminum solid solution matrix and a dispersion of Al.sub.3X precipitate having an L1.sub.2 structure where X comprises Sc, Gd and Zr. Mg is a preferred addition to the alloy containing Gd and Zr. The alloying additions control strengthening and coarsening kinetics of the alloy through control of diffusivity in the aluminum matrix and coherency strain of the Al.sub.3X precipitate.