Nanocrystalline Al-Fe alloys synthesized by high-energy ball milling

This study describes the effect of ball milling and heat treatment on the phases synthesized in a Spex mill starting from mixtures of Al and Fe powders containing 71, 75, 80 and 90 at.% Al. In the 71 and 75 at.% Al mixtures we observed the formation of the Al5Fe2 phase. At the 80 at.% Al concentration we observed the formation of an Al-rich ultrafine phase with a coherent domain size of the order of 1 nm. At the 90 at.% Al concentration, no new phase is observed to nucleate for milling times up to 50 hs. The thermal behaviour of the samples depends on the time of the milling. At all compositions, we observed the nucleation of the metastable Al6Fe compound at about 320 degrees C on heating of samples milled for short times (10 h or less) and the formation of the equilibrium phase(s) upon heating to 600 degrees C.