Structural inhomogeneities in bulk metallic glasses

该项目的目的是促进对大块金属玻璃的结构方面和机械性能的基本了解。可以预见，了解结构不均匀性在非均质流动过程中的作用，最终可以调整大块金属玻璃的延展性。在这个项目中，包括涨落电子显微镜在内的先进的电子显微镜方法将与X射线和中子散射实验以及逆蒙特卡罗模拟相结合，作为解开中期有序的主要工具。这些最先进的方法的结合，包括现场实验，有望在理解金属玻璃结构和变形机制之间的内在相互关系方面取得重大飞跃。特别是，将系统实验与建模和模拟联系起来的方法有望改善拓扑和化学异质性如何作为组成的函数和/或在变形过程中演变的图景，以及它们如何反过来控制金属玻璃中的不可逆变形。这一以联合初步研究为基础的具有挑战性的研究项目将通过维也纳大学(奥地利)和德累斯顿莱布尼茨研究所(德国)的共同努力和参与小组的跨国界专业知识来解决。为了分析这个复杂的问题，确定了以下五个关键目标：i)成分对不同大块金属玻璃(BMG)中短程有序度的作用；II)冷却速度对不同BMG结构的影响(III)机械预处理对不同BMG结构的影响(IV)结构松弛对不同状态下不同长度尺度的BMG的影响(V)用逆蒙特卡罗模拟的方法模拟BMG的结构我们建立了一个跨界项目，以探索材料科学领域的前沿，并提供玻璃结构的全面图像。这包括由热或机械前处理引起的不同长度尺度的局部变化。此外，预期的结果对于建立开发和设计性能更好的材料的原则和路线，以及最终充分挖掘块体金属玻璃作为新型结构材料的潜力具有重要意义。

The aim of this project is to advance a fundamental understanding of both the structural aspects and the mechanical properties of bulk metallic glasses. It is envisioned that understanding the role of structural inhomogeneities in the process of heterogeneous flow allows to ultimately tailor ductility in bulk metallic glasses. In this project, advanced transmission electron microscopy methods including fluctuation electron microscopy as the main tool to unravel the medium-range order will be combined with X-ray and neutron scattering experiments as well as reverse Monte Carlo simulations. The combination of these state-of-the-art methods including in-situ experiments is expected to lead to a significant leap forward in understanding the intrinsic interrelation between structure and deformation mechanisms of metallic glasses. Especially the approach to liaise systematic experiments with modelling and simulations is expected to improve the picture of how topological and chemical heterogeneities evolve as a function of composition and/ or in the course of deformation and how they in turn govern irreversible deformation in metallic glasses. This challenging research project based on joint preliminary studies will be tackled through concerted efforts and the cross-boarder expertise of the participating groups at the University of Vienna (Austria) and the Leibnitz Institute IFW, Dresden (Germany). In order to analyse this complex matter, the following five crucial goals are identified:i) Role of composition on the short-range and medium-range order of different bulk metallic glasses (BMGs)ii) Influence of the cooling rate on the structure of different BMGs (iii) Effect of mechanical pre-treatment on the structure of different BMGs (iv) Impact of structural relaxation on various length scales of BMGs in different states(v) Modelling of the structure of BMGs by the method of reverse Monte Carlo simulations Our cross-border project is set up to explore cutting-edge aspects in the field of materials science and to deliver a comprehensive picture of the glassy structure. This includes local changes at different length scales caused by thermal or mechanical pre-treatments. Moreover, the expected results are important for establishing principles and routes for the development and design of materials with improved properties and for finally exploiting the full potential of bulk metallic glasses as novel structural material.