KINETICS OF THE PRIMARY NANOCRYSTALLIZATION IN AN AMORPHOUS FE-CU-SI-B ALLOY

In situ transmission electron microscopy observations were undertaken to clarify kinetics of the primary nanocrystallization in a melt-spun amorphous Fe76Cu1Si14B9 (at.%) alloy. If was observed that the product of the primary crystallization upon annealing is a nanocrystalline al pha-Fe(Si) solid solution embedded in the residual amorphous matrix. V ariations of the alpha-Fe(Si) crystal density and its diameter respect ively with the annealing time were measured. Results show that, the al pha-Fe(Si) crystal density increases rapidly and tends to a saturated value at the early stage of the crystallization, while growth rate dec reases significantly with the crystallization proceeding. The growth o f the alpha-Fe nanophase was found to deviate from the parabolic law f or the usual primary crystallization. (C) 1997 Acta Metallurgica Inc.