A novel senary Hf-Be-Ti-Zr-Cu-Ni high entropy bulk metallic glasses with high glass forming ability and high density

New high glass-forming ability and high-density Hf20+xBe20-xTi20Zr20Cu7.5Ni12.5 (X = 1,2,3) and Hf22+2yBe18Ti20yZr20-yCu7.5Ni12.5 (y = 1,2,3,4) high entropy bulk metallic glasses (HE-BMG) were prepared by the copper mold casting method. The effect of partially substituting Be or Zr (Ti) by Hf on the glass-forming ability (GFA) and mechanical properties of HE-BMGs was investigated. The results show Hf24Be18Ti19Zr19Cu7.5Ni12.5 HE-BMG exhibits a relatively high compressive plasticity of 2.1%. Hf28Be18Ti17Zr17Cu7.5Ni12.5 HE-BMG exhibits a large GFA (critical diameter Dc = 15 mm), fracture strength (2013 MPa), and high density (8.56 g/cm3), possessing excellent overall performance. In current alloys, high-entropy effect causes atoms to sluggish diffusion, increased crystallization growth resistance and thermal stability. The partial replacement of Be or Zr (Ti) with appropriate amounts of Hf significantly increases the degree of structural heterogeneity, which results in the improvement of GFA, strength, and plasticity of HE-BMGs.