New Glassy Zr-Al-Fe and Zr-Al-Co Alloys with a Large Supercooled Liquid Region

Abstract

New Zr–Al–Co and Zr–Al–Fe ternary glassy alloys were found to exhibit a large supercooled liquid region above 50 K before crystallization. The largest value of the supercooled liquid region was 64 K for Zr₅₅Al₂₀Co₂₅ and 50 K for Zr₇₀Al₁₅Fe₁₅. The highest value of the reduced glass transition temperature (T_g⁄T_l) was 0.61 for Zr₅₅Al₂₀Co₂₅ and 0.60 for Zr₇₀Al₁₅Fe₁₅. The use of the Zr₅₅Al₂₀Co₂₅ alloy with the highest T_g⁄T_l has enabled us to form bulk glassy alloy rods with diameters up to 3 mm by copper mold casting. The Young’s modulus, yield strength, compressive fracture strength, elastic elongation and fracture elongation of the Zr₅₅Al₂₀Co₂₅ glassy rod are 92 GPa, 2050 MPa, 2200 MPa, 2.1% and 0.9%, respectively. The distinct plastic elongation indicates that the Zr-based bulk glassy alloy has rather a good ductile nature. The synthesis of the high-strength bulk glassy alloy in the new ternary system is expected to gain a new application field as a new type of bulk glassy alloy.