The extranuclear electron interaction of Finemet alloy studied by using Doppler broadening spectrum of positron annihilation

Abstract:

In this paper, we measured the Doppler broadening spectrum for positron annihilation of Finemet alloy elements and Finemet amorphous ribbons which annealed at 350℃, 380℃ and 400℃ respectively (10mins) by using two HP-Ge detector coincidence technique, in order to investigate the extranuclear electron interaction during annealing process. Results present that the peak of the ratio curve (the reference sample is Si) for asquenched Finemet ribbon is relatively low compared with those pure alloy elements Nb, Fe and Cu, because there exists a bonding between 3d orbit electrons in Fe atoms and 4d orbit electrons in Nb atoms. With the annealing temperature increasing, the peaks of ratio curves decreased and indicated that the bonding became more intensified. The strengthened extranuclear electron interaction caused that the Cu atoms tend to enrich in the surface and the Nb atoms would redistribute to the iron - rich area of amorphous ribbon.