Structure of nanocomposites of Al-Fe alloys prepared by mechanical alloying and rapid solidification processing

Structures of Al-based nanocomposites of Al-Fe alloys prepared by mechanical alloying (MA) and subsequent annealing are compared with those obtained by rapid solidification processing (RSP). MA produced only supersaturated solid solution of Fe in Al up to 10 at.% Fe, while for higher Fe content up to 20 at.% the nonequilibrium intermetallic Al5Fe 2 appeared. Subsequent annealing at 673 K resulted in more Al 5Fe2 formation with very little coarsening. The equilibrium intermetallics, Al3Fe (Al13Fe4), was not observed even at this temperature. In contrast, ribbons of similar composition produced by RSP formed fine cellular or dendritic structure with nanosized dispersoids of possibly a nano-quasicrystalline phase and amorphous phase along with α-Al depending on the Fe content in the alloys. This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP. © Indian Academy of Sciences.