Effects of additional Ag on the thermal stability and glass-forming ability of La–Al–Cu bulk glassy alloys

Abstract

The addition of Ag to La–Al–Cu ternary glassy alloys greatly increases the stabilization of supercooled liquid and glass-forming ability (GFA). The large supercooled liquid region (Δ T x ) exceeding 60 K was obtained in a wide composition range of 10–22.5 at.% Al, 15–25 at.% Cu, and 2–12.5 at.% Ag. The largest Δ T x of 83 K and the reduced glass transition temperature ( T g/ T l) were obtained for La 62.5Al 12.5Ag 5Cu 20 alloy, leading to formation of the glassy alloy sample with a diameter of 6.0 mm. The addition of small amounts of Fe or Co to La–Al–Ag–Cu alloy increases T g/ T l though the decrease in T l, resulting in an increase of GFA. As a result, the glassy alloy rods with diameters of over 7.0 mm were fabricated by addition of 2.5–5 at.% Fe or Co. The new La-based bulk glassy alloys exhibited high compressive fracture strength of 589–858 MPa with distinct plastic strain of 0.2–1.0%.