Preparation and Mechanical Properties of Zr50al5ni15cu15co15 Amorphous/Nanocrystalline Alloys

Abstract

In this paper, Zr50Al5Ni15Cu15Co15 amorphous alloy ribbons were prepared by arc melting and copper roll spinning method, and the thermal stability and tensile mechanical properties were studied. The effects of thickness and annealing temperature on the microstructure and mechanical properties were discussed. The results show that as-spun Zr50Al5Ni15Cu15Co15 alloy ribbons are amorphous, and CoZr and CuZr nanocrystals with simple cubic structures are precipitated in the amorphous matrix after annealing. At the same annealing temperature and annealing time, the thinner ribbons exhibit better the tensile strength and tensile ductility. Under the same annealing time, with the increasing annealing temperature, the grain size and volume fraction of CoZr and CuZr nanocrystals gradually increased. At the same time, the tensile strength decreased first and then increased at room temperature, and the tensile plasticity tended to increase first and then decrease. After annealing at 513 °C for 1800 s, the as-spun alloy ribbons with a thickness of 21 μm show the best comprehensive tensile mechanical properties, that the tensile strength is 1104.76 MPa and the plastic strain reaches 8.4%. The amount of nanocrystalline phase hinders the formation and expansion of shear bands, which improves the plasticity. When the annealing temperature is higher than 513 °C, the size and volume fraction of the crystal phase increase significantly, resulting in a rapid decrease in tensile strength and tensile ductility of the alloy.

Keywords: Five-element Zr-based amorphous alloy, Microstructure, annealing, Tensile mechanical properties