Ni-free Zr-based bulk metallic glasses with critical diameter above 20 mm

Glass forming ability of Ni-free Zr100−x−y(Cu5/6Ag1/6)xAly (x = 38, 40, 42, 44, 46, 48, 50 and 52 at.% and y = 6, 7, 8 and 9 at.%) alloys has been studied. It is found that bulk metallic glasses (BMGs) with a critical diameter at least 20 mm can be synthesized for quaternary Zr100−x−y(Cu5/6Ag1/6)xAly (y = 9 at.% and x = 38 at.%, y = 8 at.% and x = 42–46 at.%, y = 7 at.% and x = 46–50 at.%) alloys using copper mold casting whereas the ternary Zr48Cu45Al7 can only be cast into fully BMG with a diameter of 5 mm. The Zr46(Cu5/6Ag1/6)47Al7 BMG alloy also exhibits a plasticity of about 1.3% during compression at ambient temperature together with a yield strain of 2% and a yield strength of 1916 MPa. The developed ZrCuAgAl BMG alloys with high glass forming ability might have biomedical applications.