Al-Er
As a rare earth element, Er recently attracted research interest. The Er addition forms the L12-type precipitate Al3Er (named as AL3X, X=Er, Li, Sc, Ti, Zr). This is a stable phase and its melting temperature is higher than that of Al.
Reference
[2017Che] H.-L. Chen, Thermodynamic modeling of the Er-X (X = Ag, Al, Fe, Si, Zr) binary and Al-Er-X (X=Cu, Fe, Mg) ternary systems (Stockholm, Sweden, 2017), unpublished.