Enhancement of glass-forming ability and plasticity of Cu-rich Cu-Zr-Al bulk metallic glasses by minor addition of Dy

(Cu_0.47Zr_0.45Al_0.08) _100-xDy_x (x = 0, 1, 2, 3, 4; at.%) metallic glasses with greatly enhanced glass-forming ability (GFA) and plasticity were synthesized based on microalloying technique. The structure, thermal stability, and elastic properties of the BMG samples were studied by x-ray diffraction (XRD), differential scanning calorimetry (DSC), and ultrasonic measurements, respectively. With addition of minor dysprosium (Dy), fully metallic glassy rods with diameters exceeding 20 mm could be successfully fabricated by copper mold casting. In addition, the Cu-Zr-Al-Dy BMGs exhibit good mechanical properties under a compressive deformation mode, i.e., high yield strength of 1735-1906 MPa, Young's modulus of 85-100 GPa, and distinct plastic strain up to 4.02%. The strength and plasticity show remarkable correlations with glass transition temperature and Poisson's ratio, respectively. The role of minor Dy addition in enhancement in GFA and mechanical property of the Cu-rich BMGs is also discussed.