High-zirconium bulk metallic glasses with high strength and large ductility

In this paper, high-zirconium Zr_66+2xAl_9-x(Ni _1/3Cu_2/3)_25-x (x=0,1,2 at.%) bulk metallic glasses with high strength and large ductility were fabricated by copper mould casting. The effects of zirconium content on the glass-forming ability (GFA), thermal properties and mechanical properties were investigated using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and mechanical testing system in compressive and three-point bending modes, respectively. The high-zirconium BMGs show the critical diameters of 3-5 mm, the supercooled liquid region ranging from 70 K to 99 K, and the yield strength of over 1700 MPa. The Zr₇₀Al₇(Ni_1/3Cu_2/3) ₂₃ BMG exhibits a large compressive plastic strain up to 21% and a high notch toughness value of 60.6 MPa m^1/2. The increase in Zr content results in the decrease in GFA and thermostability, and in the improvement of plasticity under compressive and three-point bending conditions. The superior plasticity of high-zirconium BMGs is attributed to their high Poisson's ratio and small elastic modulus ratio μ/B.