Effect of metalloid substitution on the reversible structural relaxation of Fe–Ni–B(-P, Si) metallic glasses

Abstract

The reversible structural relaxation of Fe 37.5Ni 37.5B 25− x P x ( x=0, 3, 6, 16, 25) and Fe 37.5Ni 37.5B 25− y Si y ( y=0, 5, 10, 15) metallic glasses was investigated using the activation energy spectra (AES) model by differential scanning calorimetry (DSC) and resistivity measurements. From the deduced activation enthalpy spectra for these amorphous alloys, it is concluded that possibilities for atomic movements with characteristic activation energies are created by the substitution of B with P or Si. It is shown that at least one Gaussian contribution to the AES appears on increasing P or Si content, superimposed on an exponential part previously found for Fe–Ni–B glasses. The amplitude of the Gaussian function increases with increasing P or Si content while its position decreases with increasing P and remains constant with increasing Si content. According to isothermal resistivity measurements, for P substitution the reversible atomic rearrangements connected to the Gaussian contribution increase the resistivity while those associated with the exponential part decrease it. For Si substitution both processes decrease the resistivity.