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：不同的临界冷却速率可制备得到不同类型的块体金属玻璃（monolithic metallic glasses, MG）。本研究以金基金属玻璃（Au-based MG）为对象，借助快速差示扫描量热法（fast differential scanning calorimetry, FDSC）开展实验，证实金属玻璃可被划分为两类非晶/块体玻璃。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残留晶核或晶核前驱体；而第二类即所谓的化学均质玻璃（chemically homogeneous glass, CHG），则未观测到任何淬火残留结构。尽管目前已明确了上述过程的动力学特性与晶态结构的稳定性，但尚未有针对这类结构变化的直接观测报道。本研究将通过分析快速升降温过程中，搭载于快速差示扫描量热芯片传感器的高速探测器所记录的原位X射线衍射数据（倒易空间或实空间，即径向分布函数），对上述结构变化展开系统研究。