High-entropy metallic glasses (HE-MGs) recently joined the high-entropy materials and metallic glasses families as a novel class of alloys. The high-entropy effect that is believed to be crucial to HE-MGs, however, has not been well explored yet in amorphous forms. In this work, we chose a Zr₂₀Nb₂₀Cu₂₀Ni₂₀Ti₂₀ quinary HE-MG as a model system and studied its structural evolution as a function of temperature by in situ synchrotron high-energy x-ray diffraction (XRD) and extended x-ray absorption fine structure spectroscopy (EXAFS) techniques. The HE-MG exhibits irreversible structural crossover upon heating, specifically, from a relatively disordered high-energy glass state to a more ordered low-energy glass state in the supercooled liquid region but below its crystallization temperature. The pair distribution function (PDF) derived from XRD and EXAFS data suggests that the highly variable chemical short-range order (CSRO) is the underlying mechanism of the structural ordering crossover in the HE-MG. The initial ribbon sample obtained by melt-quenching has a relatively high chemical disorder with nearly random nearest atomic neighbors due to the high-entropy effect. However, the high chemical disorder is metastable upon post-fabrication heating at medium temperatures, which gradually degrades driven by enthalpy with the random neighbors replaced by more energy-favored ones. The chemical complexity of the HE-MG prevents further development of the ordering into typical crystallizations. In contrast, a conventional quinary MG with a close composition but lower entropy (Vit106, Zr₅₇Nb₅Cu_15·4Ni_12·6Al₁₀) does not show similar variable CSRO during heating. These findings demonstrate that the high-entropy effect does play an essential and unique role in HE-MGs. Competitions between entropy, enthalpy, and atomic-level stress could result in high variability in CSRO and properties, which may provide us another unexplored dimension for effectively tuning structures and tailoring properties for various applications.

高熵金属玻璃 (HE-MG) 最近作为一种新型合金加入了高熵材料和金属玻璃家族。然而，被认为对 HE-MG 至关重要的高熵效应尚未在无定形形式中得到很好的探索。在这项工作中，我们选择了 Zr ₂₀ Nb ₂₀ Cu ₂₀ Ni ₂₀ Ti ₂₀以五元 HE-MG 为模型系统，通过原位同步加速器高能 X 射线衍射 (XRD) 和扩展 X 射线吸收精细结构光谱 (EXAFS) 技术研究了其结构随温度的变化。HE-MG在加热时表现出不可逆的结构交叉，特别是在过冷液体区域但低于其结晶温度时，从相对无序的高能玻璃态到更有序的低能玻璃态。从 XRD 和 EXAFS 数据得出的对分布函数 (PDF) 表明，高度可变的化学短程有序 (CSRO) 是 HE-MG 中结构有序交叉的潜在机制。由于高熵效应，通过熔融淬火获得的初始带状样品具有相对较高的化学无序性，具有几乎随机的最近原子邻居。然而，高化学无序在制造后在中等温度下加热时是亚稳态的，其在焓的驱动下逐渐降解，随机邻居被更受能量青睐的邻居所取代。HE-MG 的化学复杂性阻止了有序进一步发展为典型的结晶。相比之下，具有接近成分但熵较低的常规五元MG（Vit106，Zr HE-MG 的化学复杂性阻止了有序进一步发展为典型的结晶。相比之下，具有接近成分但熵较低的常规五元MG（Vit106，Zr HE-MG 的化学复杂性阻止了有序进一步发展为典型的结晶。相比之下，具有接近成分但熵较低的常规五元MG（Vit106，Zr₅₇ Nb ₅ Cu _15·4 Ni _12·6 Al ₁₀ ) 在加热过程中没有显示出类似的变量 CSRO。这些发现表明，高熵效应确实在 HE-MG 中发挥了重要而独特的作用。熵、焓和原子级应力之间的竞争可能导致 CSRO 和特性的高度可变性，这可能为我们提供另一个未探索的维度，以有效地调整结构和定制各种应用的特性。