Effect of strain rate on fracture reliability of Cu₄₅Zr₄₅Co₁₀ amorphous alloy microwires by statistical analyses

The understanding of the fracture mechanism of amorphous alloys (AAs) is of importance for their engineering applications as advanced structural materials. In this study, a series of micro-tensions of Cu₄₅Zr₄₅Co₁₀ AA microwires were conducted under different strain rates ranging from 5 × 10⁻⁵ s⁻¹ to 1 × 10⁻² s⁻¹. It is found that all microwires fracture by shear cracking, but the shear fracture strengths exhibit pronounced rate-dependent uncertainties. Based on both lognormal and Weibull statistical analyses, the studied AA microwires reveal a positive rate-sensitivity of fracture strengths. However, increasing strain rates incurs the decrease in the fracture reliability. We demonstrate that the fracture reliability of AA microwires is dominated by a square root singularity of the characteristic lengths of shear offset on fracture surfaces, which satisfies linear elastic fracture mechanics.