Calorimetric and structural analysis of the Zr–Fe–Co–B–Mo–W amorphous alloys doped with gadolinium

The paper presents the calorimetric and structural analysis of the rapidly solidified GdxZr10Fe58-xCo10B15Mo5W2 (where: x = 0, 1, 2, 3, 4, 5) alloy ribbons in as-cast state. The base alloys were obtained by the arc-melting of the high purity constituent elements under a low pressure of Ar protective atmosphere. Subsequently, the ribbon samples were produced by the single-roll melt spinning technique under the low Ar pressure at the linear velocity of the copper roll surface of 32 m/s. X-ray diffraction (XRD) studies have shown amorphous structure of all the alloy. The microstructure of the samples was examined by scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) measurements were performed at various heating rates. These allowed to determine the thermal stability of the amorphous phase. The Kissinger, Ozawa and Augis-Bennett plots were constructed to determine the activation energies Ea for crystallization. The positron annihilation lifetime spectroscopy (PALS) was used to study the structural changes as well as a degree of disorder in the atomic structure caused by doping the base alloy with Gd.