The crystallization process of amorphous Al80Fe20 alloy powders prepared by ball milling

The amorphous-to-crystalline transition during thermal annealing of amorphous Al80Fe20 alloy powders prepared by ball milling was investigated by means of magnetothermal analysis and X-ray diffraction. Following structural relaxation and stress relief processes, a metastable phase precipitates during primary crystallization, and a mixture of intermetallic compound (theta-Al13Fe4) and fcc Al is developed further. On heating at constant rate annealing the first and succeeding reactions overlap to some extent in temperature. The apparent activation energy for primary crystallization amounts to 1.99 +/- 0.10 eV by using the Kissinger method. In addition, the structure of the metastable phase, which has not been identified yet, is briefly discussed. (C) 1999 Elsevier Science B.V. All rights reserved.