Effects of small amount Ta on the characteristics of the Zr-Al-Ni-Cu-Ta bulk metallic glass

The effects of Ta on the characteristics of the Zr-base BMG (bulk metallic glass) were investigated. Zr₅₅Al₁₀Ni₅Cu_30-xTa_x (x=1, 2,4) bulk metallic glasses (BMGs) with 3.5 mm diameter and 70 mm length were successfully prepared by using combined jet and copper mold casting. A small amount of Ta addition does not change the glass transition temperature, crystallization temperature,and supercooled liquid region obviously, but Ta promotes composition separation and two-stage crystallization. The stable crystalline phases include Zr₂Ni, CuZr₂, Al₂Zr₃ intermetallic compounds and Ta-rich solid solution after annealing the Zr-Al-Ni-Cu-Ta alloys at 753 K. Zr₅₅Al₁₀Ni₅Cu_30-xTa_x (x=1,2,4) bulk glassy alloys exhibit a better compressive strength. The stress-strain curve shows a zigzag feature, and the fracture surface shows intersecting of shear bands. It may correlate with the inhomogeneous feature of amorphous structure.