Radiation-induced nanostructuring of the amorphous alloy

Structural changes in the metallic glass CoFe3.2Si2.5Mn3.1B15.7, following the irradiation by Ar+ ions with the energy 30 keV at temperatures of 100–300 °C and post-irradiation annealing to a temperature of 600 °C, were studied by differential scanning calorimetry, atomic probe microscopy and electron microscopy techniques. It has been shown that irradiation at lower temperatures than the crystallization temperatures (430 and 548 °C) leads to the nanostructuring of metallic glass. The nanostructure consists of clusters sized 20–40 nm grouping together to form grains sized 100–150 nm. The nanostructure results from a heavy plastic deformation caused by ion irradiation and extends to a depth of tens of microns, much deeper than the projective ion range. The crystallization heat of this glass increases by 30% as compared to the crystallization heat of the initial non-irradiated glass. The radiation-induced formation of nanostructures is accompanied by the segregation within the glass of the metastable boride (Со3В) particles which disappear with an exothermic effect after post-irradiation annealing with return to the X-ray amorphous state.