engleski

Impact of quenched disorder and crystallization on electrical resistivity in Zr67Co33 metallic glass

The Zr67Co33 metallic glass ribbons were prepared by rapid solidification. The X-ray diffraction measurements were performed for Zr67Co33 metallic glass and confirmed the presence of a fully amorphous state. The nanocrystalline phases have been formed by the isothermal annealing of Zr67Co33 metallic glass. The crystallization of the Zr67Co33 metallic glass proceeds in three steps and three main nanocrystalline phases are found. In the first step, the nucleation of cubic Zr2Co nanocrystalline phase with the NiTi2-type structure (Fd-3 m (227) space group) is observed which is still embedded in Zr67Co33 amorphous matrix. The second step reveals the metastable orthorhombic Zr3Co2 nanocrystalline phase embedded in Zr rich amorphous matrix with nucleation of the tetragonal Zr2Co structure (I4/mcm (140)) space group. Final step reveals only the tetragonal Zr2Co nanocrystalline structure. The electrical resistivity (ρ(T)) of Zr67Co33 metallic glass and nanocrystals has been measured in the temperature range from 290 K down to 20 K. The increase of the room- temperature electrical resistivity of the samples due to annealing at temperature around the first crystallization temperature is explained as a consequence of increased disorder caused by the nucleation of cubic Zr2Co nanocrystalline phase. Both, the functional forms and the magnitudes of the observed ρ(T) of the annealed samples are interpreted in terms of weak-localization and electron–phonon interaction. We discuss the effects of the different annealing temperatures and annealing times on ρ(T) of nanocrystalline samples.

Metallic glasses ; Nanocrystals ; Transport properties ; Crystallization

nije evidentirano