Plastic Flow and Field Induced Anisotropy in Co-Base Amorphous Alloys

Plastic flow has been investigated in Co-base amorphous alloys with additive elements, Fe
3
Co
71
Si
8
B
16
M
2
, by creep measurements employing a constant-heating-rate method near the glass transition temperature. The activation energy in the creep process was found to be proportional to the atomic volume of the additive elements, which were determined from the Goldschmidt radius. The observed activation energy varied from 1.92 eV to 2.53 eV, for Co (1.25 Å) and Nb (1.47 Å), respectively. The field-induced anisotropy energy K
u
has been measured for the same alloy system. It was found that K
u
decreased with increasing atomic volume of non-magnetic additive elements. At nearly the same atomic volumes of additive elements, K
u
seemed to depend on the strength of the magnetic interaction. From these results, the degree of rearrangement of atoms and the magnetic interaction between magnetic atoms play dominant roles in determining the field-induced magnetic anisotropy.