Abstract: The eutectic microstructure of Al-Mg-Si-Re alloys and the effects of mischmetal addition on their eutectic compounds have been investigated by means of TEM, SEM and x-ray diffraelemeter. It was shown that the morpholoygies of eutectic compounds were improved and secondary deatrite arm spacing decreased by adding mischmetal. Rare earth elements dissolved in (FeSiAl) phase, and the ( ReFeSiAl ) phase and the Re2Si2Al8 compound occurred in the alloys containing 0.07～0.20wt％ Re Al4Re phase was not found in the alloys unless the Re content was more than 0.2wt％.

Key words: 变形铝合金, 共晶化合物, 共晶组织, 稀土, 稀土化合物