It has long been recognized that the relaxation spectrum of glassy solids is intrinsically connected to their disordered structural features and deformation behaviors. However, such connections still remain elusive for metallic glasses. Here, through the extensive study of a variety of metallic glasses over a wide range of temperatures, we provide the compelling evidence for the existence of a universal fast secondary relaxation process, which occurs at a temperature far below the glass transition point with a low activation energy (0.3–0.6 eV). Furthermore, it is demonstrated that the initiation of plasticity in metallic glasses is strongly correlated with the fast relaxation process. By exciting the fast relaxation process, multiple shear banding is triggered as opposed to single shear banding in the metallic glasses, which leads to an unusual brittle-to-ductile transition in malleability, being fundamentally different from the ordinary one commonly observed in crystalline alloys. Furthermore, our results shed the quantitative insights into the atomistic mechanisms that differentiate brittle from plastic metallic glasses at different temperatures.

中文翻译：

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金属玻璃中的普遍二次弛豫和不寻常的脆韧转变

人们早就认识到玻璃状固体的弛豫谱与它们的无序结构特征和变形行为有着内在的联系。然而，对于金属玻璃来说，这种联系仍然难以捉摸。在这里，通过在广泛的温度范围内对各种金属玻璃的广泛研究，我们为普遍快速二次弛豫过程的存在提供了令人信服的证据，该过程发生在远低于玻璃化转变温度的低活化温度下能量 (0.3–0.6 eV)。此外，证明金属玻璃塑性的开始与快速弛豫过程密切相关。通过激发快速弛豫过程，触发了多重剪切带，而不是金属玻璃中的单剪切带，这导致延展性出现异常的脆-韧转变，与通常在结晶合金中观察到的普通转变完全不同。此外，我们的结果揭示了在不同温度下区分脆性与塑料金属玻璃的原子机制的定量见解。