Structural relaxation and nanocrystallization of amorphous Finemet alloy investigated by positron annihilation techniques

The structural relaxation and nanocrystallization of amorphous Finemet alloy during annealing have been investigated by positron annihilation techniques. There are two types of defects in the amorphous and nanocrystalline Finemet alloys. The change of structural defects is mainly due to the structural relaxation, the pre-nucleation of Cu nucleus and the nanocrystallization of α-Fe(Si) phase during annealing. The variations and values of the two components (I1 and I2) are very similar to the volume fractions of the residual amorphous matrix (Va) and nanocrystalline phase (Vc). It seems that there are some intrinsic relations between the volume fractions of amorphous phase and nanocrystalline phase and the intensities of two components. There are more defects in the nanocrystallized Finemet alloy than in the as-quenched state and the nanocrystallization process introduces many defects.