MECHANICAL ALLOYING OF FE-AL INTERMETALLICS IN THE DO3 COMPOSITION RANGE

Binary Fe-Al intermetallics with compositions ranging between 10 and 3 0 at % have been produced by mechanical alloying. The elemental powder s were milled together resulting in the dissolution of the Al atoms in to the Fe lattice. Subsequent heat treatment of the compacted powder r esulted in the formation of the intermetallic. However, complete suppr ession of the DO3 (Fe3Al) structure in favour of the B2 (FeAl) structu re was observed. The suppression of the DO3 structure is considered to be due to the presence of the high density of defects resulting from the heavy deformation incurred during milling. At Al compositions belo w 22 at %, X-ray diffraction revealed a b c c phase with lattice param eters varying between those of alpha-Fe and the B2 intermetallic. The structure tended towards that of alpha-Fe with lower Al contents indic ating a decreasing number of Al atoms available to occupy B2 lattice s ites. A fine grain size and evidence of tearing indicate that mechanic ally alloyed Fe-Al intermetallics in the DO3 composition range are duc tile at room temperature.