Formation of Zr–Co–Al bulk metallic glasses with high strength and large plasticity

A series of Zr56Co44−xAlx (x = 12, 14, 16 and 18, respectively) bulk metallic glasses (BMGs) are obtained using water-cooled copper mold casting technique. With increasing Al/Co ratio, the BMGs exhibit a better thermal stability of the supercooled liquid, higher strength and larger plasticity. The origin of the high specific fracture strength lies in the increased strength and reduced mass density (more Al). Among them, Zr56Co26Al18 BMG has a high fracture strength (∼2477 MPa), small density (∼6.31 g/cm3) and very high specific fracture strength (∼3.92 × 105 Nm kg−1) exceeding the values of commercial stainless steel, light alloys as well as some popular BMGs. It seems to be a promising structural material owning to its excellent GFA, large plasticity and high specific strength.