Glass-forming ability and crystallization behavior of Co62−xFexNb6Zr2B30 (x=0,16) amorphous alloys with large supercooled liquid region

Abstract

The kinetics of the glass transition and the crystallization process of ${\mathrm{Co}}_{\text{62−x}}{\mathrm{Fe}}_x{\mathrm{Nb}}_6{\mathrm{Zr}}_2{\mathrm{B}}_{30}$ $\text{(x=0,16)}$ amorphous alloys with large supercooled liquid region was investigated by differential scanning calorimetry. The dependence of the glass transition on the heating rate was analyzed in terms of the Vogel–Fulcher–Tamman equation. The glass-forming ability of these alloys is discussed with respect to the width of the supercooled liquid region, the reduced glass transition temperature, and the fragility parameter. The studied alloys are found to be rather strong glass formers. The crystalline phases formed after the devitrification are identified by means of x-ray diffraction and thermomagnetic measurements. The complicated crystallization process requiring long-range atomic rearrangements seems to contribute to the high stability of the supercooled liquid against crystallization.