Structural Analysis of Amorphous Fe–B Alloys on the Basis of Plasma Losses

The change of free electron densities in amorphous Fe–B alloys and their crystallized phases on the basis of the volume plasmon energies. The purpose of this study was to discuss the chemical bonding from the differences of electronic structures between amorphous and crystalline phases and to reveal the correlation between the formability of amorphous solids and the chemical bonding.Electron energy loss spectroscopy, combined with transmission electron microscopy, was used for electronic and atomic structure measurements.The results showed that the free electron densities decreased with increasing B content, and as compared two atomic structures in the same compositions, the free electron density of the amorphous phase was higher than that of the crystalline phase. The covalent bonding was dominant in the crystalline phase, however the Fe–Fe metallic bonding became tighter in the amorphous phase and two kinds of bonding states were present microscopically as a mixture. The formability of amorphous solids has been found to depend on the compositions since amorphous phases can be formed under the well-balanced conditions of two kinds of bonding states.