To improve the ductility of Al 3 Hf and Al 3 Ta intermetallic compounds, which are the potential temperature structural materials, the mechanical alloying behaviour and the effect of ternary additions on the Ll 2 phase formation were investigated. During the mechanical alloying by the SPEX mill, the Ll 2 Al 3 Hf intermetallic compound was formed after 6 hours of milling in AL-25%Hf system. In AL-25%Ta system, however, only the D0 22 Al 3 Ta intermetallic compound was formed until 30 hours of milling and the Ll 2 phase was not observed. In AL-12.5%M-25%Ta(M=Cu, Zn, Mn, Fe, Ni) systems, the additions of Cu and Zn had no effect on the D0 22 structure of the binary Al 3 Hf and the additions of Mn, Fe and Ni produced the amorphous phase. Therefore it was considered that these ternary additions could not overcome the energy difference between Ll 2 and D0 22 structures in the Al 3 Hf intermetallic compound. In AL-12.5%M-25%Hf(M=Cu, Zn, Mn, Fe, Ni)systems, the additions of Cu and Zn did not affect the Ll 2 structure of the binary Al 3 Hf but the additions of oMn, Fe and Ni produced the amorphous phase as they did in AL-12.5%M-25%Ta systems. Therefore, it was considered that the Ni, Mn and Fe additions promote the formation of amorphous phase in Al 3 X intermetallic compounds.