Microscopic structure and dynamics of bulk metallic glass-forming liquids with minor additions

在当前的项目中的微观动力学，粘度，Zr-Cu熔体的结晶行为进行了研究，分别采用准弹性中子散射，振荡滴技术，和原位同步辐射衍射，所有结合无容器处理技术的静电悬浮。我们能够表明，合金化少量的Al，4原子%，显着改变的动力学，以及从深过冷熔体在Zr 50 Cu 50液体的凝固行为。相比之下，少量Ti添加对熔体动力学的影响要小得多。第一分子动力学模拟表明，Al添加后的熔体动力学的强成分依赖性可能有其起源在液体的介质范围。因此，预计化学短程有序的贡献在熔体中也将发挥重要作用。为了验证这一假设，i）我们打算合金化第三种非金属元素，如Si（而不是Al），其中电子相互作用的影响在金属/非金属原子对中甚至更占主导地位，并应用ii）波动电子显微镜（FEM）来解决关于微量添加物对玻璃形成能力的结构作用的重要问题。结合理论和模拟，该项目旨在通过确定微量添加剂在增强二元合金玻璃形成能力方面所起的关键微观作用，更好地了解大块金属玻璃形成的性质。在续篇的框架内，Szabo先生将完成他的博士论文。

Within the current project the microscopic dynamics, viscosity, and the crystallization behavior of the Zr-Cu melts have been studied employing quasielastic neutron scattering, oscillating drop technique, and in-situ synchrotron diffraction, respectively, all combined with the containerless processing technique of electrostatic levitation. We were able to show that alloying a small amount of Al, 4 at %, notably alters the dynamics, as well as the solidification behavior from deeply undercooled melt at Zr50Cu50 liquid. In contrast, the impact of a small Ti addition on the melt dynamics is considerably smaller. First molecular dynamics simulations indicate, that the strong compositional dependence of the melt dynamics upon Al addition may have its origin in the medium range of the liquid. Hence, contributions from chemical short-range order are expected to play an important role in the melt, too. To test this hypothesis i) we intend to alloy a third, non-metallic element like Si (instead of Al) where the impact of the electronic interactions would be even more dominant in metal/non-metal atomic pairs and to apply ii) fluctuation electron microscopy (FEM) to address the important question as to the structural role of the minor addition on glass-forming ability. Together with theory and simulation, this project seeks to better understand the nature of bulk metallic glass formation by identifying the key microscopic role played by the minor addition in enhancing the glass-forming ability of binary alloys. In the framework of the continuation Mr. Szabo will finish his PhD thesis.