Direct observation of structural changes in chemically homogeneous and self-doped metallic glasses upon in-situ ultrafast heating and cooli

Recently, our group has shown the existence of multiple critical cooling rates which generate different types of monolithic metallic glasses. Via fast differential scanning calorimetry (FDSC), using a Au-based MG as an example, we proved that MGs should be classified into two types of amorphous/monolithic glass. The first type, termed self-doped glass (SDG), forms quenched-in nuclei or nucleation precursors upon cooling, whereas in the so-called chemically homogeneous glass (CHG) no quenched-in structures are found. Although the kinetics of these processes and the stability of the crystalline structures were established, there is no direct observation of the structural changes. These changes will be investigated by analyzing in-situ X-ray diffraction data (reciprocal space or direct space, i.e. pair distribution functions) as recorded with a fast detector upon rapid heating and cooling with the help of a FDSC chip sensor.

近期，本团队证实了多种临界冷却速率的存在，此类速率可制备得到不同类型的整体金属玻璃（monolithic metallic glasses）。我们以金基金属玻璃（Au-based MG）为研究范例，借助快速差示扫描量热法（fast differential scanning calorimetry, FDSC）证明，金属玻璃（MG）可被划分为两类非晶/整体玻璃：第一类被命名为自掺杂玻璃（self-doped glass, SDG），在冷却过程中会形成淬火引入的晶核或成核前驱体；而另一类所谓的化学均质玻璃（chemically homogeneous glass, CHG）则未观测到任何淬火引入的结构。尽管目前已明确了该类过程的动力学特征与晶态结构的稳定性，但尚未有针对此类结构变化的直接观测结果。本研究将通过分析原位X射线衍射（in-situ X-ray diffraction）数据展开相关探究，此类数据可通过快速探测器采集，涵盖倒易空间（reciprocal space）与实空间（direct space，即对分布函数pair distribution functions）两类形式，实验过程将依托FDSC芯片传感器实现快速升降温操作。