Effect of thermal treatment on the atomic ordering of mechanically alloyed Al3Nb

The present study was carried out to investigate the effect of thermal treatment on the atomic ordering of mechanically alloyed Al3Nb. The partially disordered Al3Nb alloy is transformed into an ordered IO-nm sized Al3Nb after a following heat treatment. The value of DeltaH(order) for ordering of Al3Nb intermetallics is more negative for faster heating rates and prolonged milling time. The average values of DeltaH(order) correspond to about 35% of the DeltaH necessary for Al3Nb phase formation. The activation energies for ordering of Al3Nb at 30 and 40 h of milling an relatively close to the isothermal grain growth enthalpy of nanocrystalline Al3Nb intermetallics. (C) 2000 Elsevier Science B.V. All lights reserved.