Effect of silicon addition on the glass-forming ability of a Zr-Cu-based alloy

The effect of Si addition on the glass-forming ability (GFA) of (Zr47Cu44Al9)100−xSix (x = 0, 0.5, 1, 1.5, and 2.5) metallic glass alloys was investigated by using X-ray diffraction (XRD), optical microscopy, and differential scanning calorimetry (DSC). The maximum diameter of glassy rods increased from 4 mm for the Zr47Cu44Al9 alloy to 6 mm for the (Zr47Cu44Al9)98.5Si1.5 alloy without detectable crystallinity when prepared using copper mould casting. Different criteria are used to evaluate the influence of Si content on the GFA. Due to the suppression of the formation of the primary CuZr phase and the induction of the composition close to the eutectic point, properly adding Si can enhance the GFA of the (Zr47Cu44Al9)100−xSix alloy. The possible mechanisms involved in the achievement of this GFA are also discussed.