Fig. 1

The notch fracture toughness of metallic glasses exhibits a dramatic transition as a function of fictive temperature, T_f. a The notch fracture toughness K_Q, normalized by its minimal value K_Q,min, as a function of T_f, normalized by the glass temperature T_g, for Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ (black squares), Pd₄₃Cu₂₇Ni₁₀P₂₀ (red circles), and Pt_57.5Cu_14.7Ni_5.3P_22.5 (blue triangles). The error bars represent 1 standard deviation of five samples per data point. The dashed lines serve as a guide to the eye. b K_Q for Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ as a function of T_f (measured at room temperature, black symbols—bottom axis) and T (red symbols—top axis, measured at T) with T_f = 683 K >\(T_{\mathrm{f}}^{\mathrm{DB}}\) (red circles) and T_f = 583 K <\(T_{\mathrm{f}}^{\mathrm{DB}}\) (red triangles)_. The dashed lines represent polynomial fits of the data. c The plastic zone ahead of the notch root just prior to failure of Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ for several T_f. Dimension lines indicate the plastic zone size. For T_f < \(T_{\mathrm{f}}^{\mathrm{DB}}\), the plastic zone is small, while for T_f > \(T_{\mathrm{f}}^{\mathrm{DB}}\) it is significantly larger. The plastic zone is symmetric with respect to the main axis of the notch (darker areas are optical effects). The scale bars are 100 μm. d The fracture morphology of Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ for various T_f. As the threshold \(T_{\mathrm{f}}^{\mathrm{DB}}\) is surpassed (top right), the fracture morphology changes from fractal-like structures (characteristic of brittle-like fracture) to river-like patterns (characteristic of ductile-like fracture). The scale bars are 50 μm