Composition optimization of the Cu-based Cu-Zr-Al alloys

The present paper is concerned with the formation of the Cu-based Cu-Zr-Al bulk metallic glasses (BMGs). Composition optimization for BMG formation was realized by using an 'e/a-variant criterion' that had been successfully applied in the Zr-Al-Ni and Zr-Al-Co systems, This criterion was incorporated into the ternary phase diagram by constructing a composition line (Cu _61.8Zr_38.2)_1-xAl_x, which was defined by linking the optimum binary composition (Cu_61.8Zr_38.2, a deep eutectic in this case) and the third element. BMGs were obtained within an e/a span from 1.24 to 1.3 along this composition line. Thermal analysis results indicate that these BMGs manifest increased thermal stability and glass forming ability (GFA) with increasing e/a ratios. The maximum appears in Cu _58.1Zr_35.9Al₆ with the e/a value of 1.3 which is the highest among our samples. The characteristic thermal parameters of this BMG are T_g=760 K, T_g/T₁=0.648, which are all superior to those reported for the known Cu₅₅Zr₄₀Al ₅ BMG. © 2004 Elsevier Ltd. All rights reserved.