Effects of additional elements (M) on the thermal stability and structure of (Zr_52.2Cu_39.1Al_8.7)_100-x M _x (M = Ag, Be, Gd, x = 8, 7, 2) amorphous alloys

The effects of Ag (8 at.%), Be (7 at.%), and Gd (2 at.%) addition on structure and thermal stability, as well as bulk glass forming ability, in (Zr_52.2Cu_39.1Al_8.7)_100-x M _x (M = Ag, Be, Gd) alloys are investigated by means of X-ray diffraction and differential scanning calorimetry. The alloy containing Ag and Be have a critical diameter of more than 10 mm, with larger supercooled liquid region and atomic packing efficiency than Zr_52.2Cu _39.1Al_8.7 alloy, while the (Zr_52.2Cu _39.1Al_8.7)₉₈Gd₂ alloy only has a critical diameter of up to 5 mm and shows smaller supercooled liquid region and atomic packing density. CuZr is the main competing crystal phase with amorphous phase in the present Zr-Cu-based alloys. Ag and Be atoms in Zr _52.2Cu_39.1Al_8.7 alloy decrease the long range diffusion of Cu atoms and hinder the crystallization process under rapid solidification conditions. As a result, the glass forming ability of (Zr _52.2Cu_39.1Al_8.7)₉₂Ag₈ and (Zr_52.2Cu_39.1Al_8.7)₉₃Be₇ alloys are effectively enhanced.