The study on the electronic structure and the crystallization process of metal-metal amorphous alloys

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The purpose of this study is to investigate the electronic structure in amorphous CuZrFe alloys and its stability. Specimens were prepared by single roll method. In specimens with low Fe concentration @>D157@>D1Fe was enriched.1. The results on Cu_<60>Zr_<40> and Cu_<59>Zr_<40>Fe_1 : The Mossbauer spectrum showed a doublet peak whose split was large. The shape and parameters of the peak was similar to those for Fe-Zr intermetallic compounds or especially amorphous Fe_<25>Zr_<75>. From those results it is concluded that around Fe atoms Zr atoms were ditributed and that the electronic structure in amorphous Cu_<60>Zr_<40> is similar to that in amorphous Fe_<60>Zr_<40>. The crystallization process has one stage judging from DSC analysis. However the Mossbauer spectrum change during crystallization showed two stages at least. Before crystallization Debye temperature, quadrupole splitting and isomer shift changed a little. Amorphous Cu_<59>Zr_<40>Fe_1 crystallized by annealing at 773K for 30minutes. The quadrupole splitting decreased abrptly. This means that the asymmetry in amorphous decreased with crystallization. The shift of isomer shift to plus side with the crystallization indicates the increase of d electrons in Fe.2. The results on Cu_<60-x>Zr_<40>Fe_x(1 x 20). The stability of amorphous decreased with in creasing Fe concentration. The activation energy of crystallization was 5.8eV for Cu_<59>Zr_<40>Fe_1 and 3.9eV for Cu_<40>Zr_<40>Fe_<20>. It was diffcult to obtain amorphous structures with high Fe concentration. Debye temperature, quadrupole splitting and isomer shift decreased with increasing Fe. These changes are related with stability. The replacement of Fe to Cu decreases d electrons in amorphous. So d electrons in Fe decreased. To stabilize the amorphous structure the bonding between Fe or Cu and Zr is necessary. The bonding owes to d electrons. The defficiency of d electrons with increasing fe make amorphous structure unstable.