MECHANICAL ALLOYING OF IRON-ALUMINUM INTERMETALLICS

The intermetallic Fe3Al has been produced by the heat treatment of mechanically alloyed iron and aluminium powders. X-ray diffraction analysis of the mechanically alloyed powder revealed the presence of a mixture of the intermetallic FeAl and elemental iron. Following subsequent heat treatment, only the B2 (FeAl) structure was detected. This is unusual since the actual chemical composition of the compound was that of Fe3Al (D0(3)). Mechanical alloying is a technique which introduces a very large degree of structural damage and the high number of defects created are responsible for the production of the B2 structure in preference to the D0(3) structure. Comparison has been made with the same material produced by rapid solidification, since a similar disordering effect has been observed using this technique. Hardness testing of the heat treated material indicated that the intermetallic produced by mechanical alloying is ductile and this has been attributed to a very fine grain size and good homogeneity. (C) 1993 The Institute of Materials.