Co substituted Zr-Cu-Al-Ni metallic glasses with enhanced glass-forming ability and high plasticity

Zr-based bulk metallic glasses have been considered as promising engineering materials. However, their widespread application is limited by their contrasting properties of glass-forming ability (GFA) and plasticity. Herein, the effects of Ni substitution by Co on the GFA and plasticity of the representative Zr-based metallic glass of Zr₆₅Cu_17.5Al_7.5Ni₁₀ were investigated. A series of Zr₆₅Cu_17.5Al_7.5Ni_{10 − x}Co_x (x = 0, 2, 4, 6, 7, 8, 10) rod samples with 2 mm in diameter were prepared by injection copper mold casting method. Amorphous structure was successfully achieved when the Co content is less than 8 at.%. Importantly, the Co addition contributed to significant enhancements in both GFA and plasticity of the amorphous Zr₆₅Cu_17.5Al_7.5Ni_{10 − x}Co_x (x = 0, 2, 4, 6, 7) alloys. The as-prepared Zr₆₅Cu_17.5Al_7.5Ni₈Co₂ amorphous alloy shows the best and attractive performance with a supercooled liquid region width of 80 K and a compressive plasticity of 7.4%, which are much higher than 50 K and 0.2% of the pristine Zr₆₅Cu_17.5Al_7.5Ni₁₀ amorphous alloy, demonstrating that the Co substituted Zr-Al-Ni-Cu metallic glass has the potential to be used for engineering applications.