Effect of molybdenum substitution on crystal structure of ordered Fe–Al alloys

The substitution behaviour of molybdenum in B2 and D0₃ Fe–Al alloys having aluminium contents between 22 and 37 at.-% has been investigated using differential thermal analysis and X-ray diffraction. It is shown that low (5%) substitution of molybdenum for iron resulted in a significant (up to 175°C) increase in both B2 and D0₃ ordering temperatures, but larger (10 and 15%) additions of molybdenum did not continue this trend to the same magnitude due to the formation of molybdenum rich precipitates. It was shown using X-ray diffraction that molybdenum substitutes for iron on the B sites of the D0₃ structure and on the B/C sites for the B2 structure. The increase of B2 and D0₃ ordering temperatures is interpreted in terms of changes in bonding behaviour in bcc, B2, and D0₃ structures resulting from molybdenum substitution.

MST/1716