Nanocrystallisation of amorphous alloys: comparison between furnace and current annealing

The mechanism of nanocrystallisation of the amorphous Fe72CU1Nb4.5Si13.5B9 alloy has been studied with particular attention to the early stages of cry stallisation, The specimens have been nanocrystallised by furnace (FA) and current (CA) annealing and analysed by Mossbauer spectroscopy. X-ray scatte ring, using the beamline 5.2L at Elettra Synchrotron Source, Trieste, has b een carried out on the same FA and CA samples, as well as on a previously u ntreated sample current heated in situ. It is found that for the same amoun t of nanocrystalline phase, the crystallite size in CA samples does not dif fer significantly from that in FA samples, Analysis of the Mossbauer spectr a shows that in FA and CA samples the nanocrystalline grains consist of non -stoichiometric partially disordered Fe3Si phase, and that there is an indi cation of the presence of boron atoms in the nanocrystals of CA samples. Th is implies a lower segregation of boron atoms or of borides at the boundari es of nanocrystallites of CA samples and can be connected to their lower br ittleness. (C) 2000 Elsevier Science Ltd. All rights reserved.