Cu-Based Bulk Glass Formation in the Cu-Zr-Ga Alloy System and Their Mechanical Properties

Abstract

The thermal stability, glass-forming ability (GFA) and mechanical properties of a new Cu-based glassy alloy in Cu-Zr-Ga ternary system have been investigated. The supercooled liquid region ΔT_x(= T_x − T_g) exceeding 40 K and reduced glass transition temperature (T_g/T_l) above 0.59 are obtained simultaneously in the composition range from 2.5 to 7.5%Ga and 37.5 to 42.5%Zr, and the highest T_g/T_l is 0.62 for Cu_52.5Zr_42.5Ga₅ and Cu₅₅Zr₄₀Ga₅ alloys. The Cu-based Cu-Zr-Ga glassy alloys are formed in a rod form with a diameter up to 2.0 mm by the copper mold casting. The bulk glassy alloys exhibit good mechanical properties of 550-580 for Vicker's hardness (H_v), 105-111 GPa for Young's modulus (E), 1910-2130 MPa for compressive fracture strength (σ_c,f), and 0.2-0.5% for plastic elongation. The GFA of Cu-based Cu-Zr-Ga glassy alloys is more closely related to T_g/T_l values rather than ΔT_x. The present new Cu-based bulk glassy alloys are expected to be developed as another type of bulk structural material with higher strength combined with good ductility.