A series of Dy（Gd）-based bulk amorphous alloy rods were prepared by water-cooled copper mold method. Thermal stability and structure of Dy-Gd-Co-Al alloys were investigated by differential scanning calorimetry and X-ray diffraction, respectively. The results show that the Dy-Gd-Co-Al alloys have good glass-formation ability, and the Dy31Gd25Co20Al24 alloy can be readily cast into full glassy rods up to 5 mm in diameter. The glass-forming ability of multicomponent alloys was greatly dependent on their chemical interaction and the equivalent bond parameters among atoms such as equivalent electronegativity difference, equivalent atomic size parameter. The Dy （Gd）-based bulk amorphous alloys could be expected as potential functional materials.
A series of dysprosium-based ternary, quadruple, and quintuple bulk metallic glasses （BMGs） based on Dy-Al binary eutectic composition were obtained with the partial substitution of Co, Gd, and Ni elements, for dysprosium. The results showed that the Dy31Gd25Co20Al24 alloy, which had the best glass forming ability （GFA）, could be cast into an amorphous rod with a diameter of 5 ram. The GFA of alloys was evaluated on the basis of the supercooled liquid region width, 7 parameter, the formation enthalpy, and the equivalent electronegativity difference of amorphous alloys. It was found that the eutectic composition was closely correlated with the GFA of the Dy-based BMGs.
