The crystallization of the amorphous alloys Fe 7 5 - x Cu x Si 9 B 1 6 (x =< 4) is completed in three stages: (a) dendritic growth of bcc Fe[Si,Cu], (b) eutectic crystallization of bcc Fe[Si,Cu] + bct Fe 3 B and, finally, (c) formation of bct Fe 3 B. The metastable compound Fe 3 B formed during the second and third stages is eventually dissolved into bcc Fe and bct Fe 2 B. As Cu atoms replace Fe atoms, the kinetics of the whole process is modified because of microsegregation: the first stage is decelerated, the second is accelerated, and the third is accelerated up to 2 at% Cu, but is decelerated at higher concentrations.