The magnetic susceptibility and peculiarities of the optical conductiv
ity spectrum for Ni78SixB22-x and Ni80Si10B10 amorphous ribbons have b
een studied to find the thermostability factors among the dynamic and
kinetic characteristics of electrons in the near-Fermi-level range. Th
e obtained experimental data have shown that for the alloys with high
thermostability the density of electronic states at the Fermi level te
nds to decrease while the scattering cross section of free charge carr
iers increases.