金属玻璃的液态结构及其动力学胶体模拟

研究金属玻璃对于改善性能,开发新的合金体系有重要意义。由于实验手段的局限,目前为止还未能直接观测到液态结构的演化过程。胶体体系可以得到直观可视的粒子图像,已被应用于模拟研究原子体系的物理变化过程。通过不同的胶体体积浓度来模拟金属玻璃熔体,分析了不同胶体液态体系中的团簇结构,并对胶体粒子的扩散规律进行了探讨。结果表明液态体系的浓度越高,粒子的扩散速率越慢,局域特征结构发生变化,并在高浓度液态结构中观察到了结构的局域有序性动力学阻滞形成的笼子效应,为胶体体系液态微结构随浓度的演化提供了直接的实验证据。

Local Structural Evolution in Liquid Metallic Glasses by Colloidal Model

Structure of metallic glasses (MGs) has been a fascinating mystery in a long history. Evolution of microstructures in liquid state has not been observed yet. Colloidal systems have been used to investigate atomic system experimentally attributing to the much bigger size of colloidal particles than atoms, resulting in direct visualization under microscope. In this work, colloidal systems in different concentration were investigated to simulate liquid state and glassy state of real alloy systems. Single component colloidal systems in liquid state were achieved. Clusters structures and diffusion dynamics were studied. The results show that at higher liquid concentration, the diffusion and movement of particles are much slower. The number of clusters both in hexagon and heptagon shape increase while in pentagon shape decrease with concentration. Practically, for higher concentration system, local order orientation was observed. Meanwhile cage effect because of structure arrest was obtained. It is indicated that when approaching concentration for glass transition, the microstructures inside the liquid system are very unstable.