Micro- and macroscopic magnetic study of the disordering (ball milling) and posterior reordering (annealing) of Fe-40 at.% Al

The paramagnetic-ferromagnetic transition of Fe-40 at.% Al during ball mill ing, from 0 to 72 h, (disordering process) and the posterior ferromagnetic- paramagnetic transition with subsequent annealing, from T-ANN = 300 to 975 K, (reordering process) were studied by magnetization and Mossbauer spectro scopy to understand the differences between local and average properties in nanometric systems. The overall properties observed from both techniques a re similar despite the atomic scale data of Mossbauer spectroscopy and macr oscopic properties measured by magnetization, respectively. The differences between both types of results, e.g., 10-20% larger paramagnetic contributi on or 10-20% smaller normalized hyperfine field - magnetization observed fr om Mosbauer spectroscopy, are a consequence of the microscopic-macroscopic length scales of each technique and the limitations of the data analysis. ( C) 2001 Published by Elsevier Science B.V.