Influence of Fe addition on glassy stability of an Al₈₅ Ni₅Y₈Co₂ metallic glass with a large supercooled liquid region

The effect of Fe additions on glass formation and stability of an amorphous Al₈₅Ni₅Y₈Co₂ alloy with a large supercooled liquid region has been studied using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. It was found that the Fe content significantly affects the primary crystallization kinetics of this alloy, but little on its glass-forming ability (GFA). Interestingly, an Al₈₅Ni₅Y₆ Fe₂Co₂ glassy alloy, with a wide supercooled liquid region of 24 K and a superior stability against primary crystallization up to 570 K, was synthesized. Its devitrification kinetics appears to be proceeded by two-stage primary reaction over the temperature range of 570-645 K through a continuous process of the nucleation and growth of Al nanocrystals, followed by the concurrence of Al₃(Ni, Fe), Al₉Co₂ and Al₃Y intermetallics. The formation of such a more stable glass due to partial replacement of Y by Fe in Al₈₅Ni₅Y₈ Co₂ is proposed to be associated with the amorphous structure and the solute concentration distribution feature. © 2005 Elsevier B.V. All rights reserved.