Formation and mechanical properties of Zr-Nb-Cu-Ni-Al-Lu bulk glassy alloys with superior glass-forming ability

Glass-forming ability (GFA) and mechanical properties of (Zr_0.58Nb_0.03Cu_0.16Ni_0.13Al_0.10)_100-xLu_x (x = 0-3 at%) alloys have been investigated. The GFA of Zr₅₈Nb₃Cu₁₆Ni₁₃Al₁₀ alloy is dramatically enhanced by adding Lu. The (Zr_0.58Nb_0.03Cu_0.16Ni_0.13Al_0.10)₉₈Lu₂ alloy possesses the highest GFA in the studied Zr-Nb-Cu-Ni-Al-Lu alloys, with its critical diameter for glass formation reaching 20 mm by copper-mould casting method, while that of the Lu-free Zr₅₈Nb₃Cu₁₆Ni₁₃Al₁₀ alloy is 7 mm. The critical diameters of (Zr_0.58Nb_0.03Cu_0.16Ni_0.13Al_0.10)100-xLux (x = 1 at% and 3 at%) alloys are 15 mm and 12 mm, respectively. The Lu addition to Zr₅₈Nb₃Cu₁₆Ni₁₃Al₁₀ alloy induces the change of initial crystallization phases from face-centred-cubic Zr₂Ni and tetragonal Zr₂Ni phases for the Lu-free Zr₅₈Nb₃Cu₁₆Ni₁₃Al₁₀ alloy to an icosahedral quasi-crystalline phase for the Lu-doped alloys, which may be the origin for the enhanced GFA of the Lu-doped alloys. The compressive fracture strength and plastic strain of the bulk glassy (Zr_0.58Nb_0.03Cu_0.16Ni_0.13Al_0.10)₉₈Lu₂ alloy are 1 610 MPa and 1.5%, respectively.