A comparative study of glass-forming ability, crystallization kinetics and mechanical properties of Zr55Co25Al20 and Zr52Co25Al23 bulk metallic glasses

Most bulk metallic glass systems with high glass-forming ability are doped with precious metal(s) or toxic element(s), like palladium and beryllium, leading to relatively high cost or low safety in use. In this work, the glass-forming ability, crystallization kinetics and mechanical properties of the Zr55Co25Al20 and Zr52Co25Al23 bulk metallic glasses prepared by water-cooled copper mold suction casting are investigated in detail. The results show that Zr52Co25Al23 has a wider supercooled liquid region, a higher thermal stability and a higher glass-forming ability than the Zr55Co25Al20 amorphous alloy. At the same time, Zr52Co25Al23 has a higher activation energy of crystallization than Zr55Co25Al20 amorphous alloy, indicating that Zr52Co25Al23 has a higher resistance to crystallization than Zr55Co25Al20. Investigation of the mechanical properties reveals that Zr52Co25Al23 also has a higher fracture strength of up to 2308 MPa and a higher specific fracture strength of up to 3.78 x 10(5) N m kg(-1) compared with 316L stainless steel, Ti-6Al-4V, as well as Mg-, Ti-, and other Zr-based BMGs. (C) 2019 Elsevier B.V. All rights reserved.