Microstructure and Stability of Metallic Nanoglasses

金属纳米玻璃是具有显著增加的过量体积的致密玻璃。它们可以通过固结非晶金属纳米颗粒来合成，并且表现出明显不同于相同组成的熔融纺丝块体玻璃的性质分布。通过分子动力学模拟的二元模型玻璃（Cu-Zr），我们可以表明，玻璃-玻璃界面的特点是由修改后的本地秩序和过剩体积类似的剪切带中发现的塑性变形。实验研究的Fe-Sc玻璃表现出明显的机械和磁性能的修改，并显示在微观结构中的纳米结构元素。本研究项目的主要目标是获得纳米玻璃微观结构特征的一致图片。我们的主要科学目标是了解实验观察到的大规模密度波动的物理起源，并找到纳米玻璃意外热稳定性的原因。特别是，我们将研究在冷压过程中发生的烧结机制，通过改变颗粒尺寸，压力和材料。在实验上，我们将扩展我们的研究，非磁性Pd-Si，这也可以通过经典的分子动力学模拟来描述，而电子结构计算的Fe-Sc在双晶体几何形状将有助于量化的实验结果。

Metallic nanoglasses are dense glasses with a significantly increased excess volume. They can be synthesized by consolidating amorphous metallic nanoparticles and exhibit a property profile that is clearly different from a melt spun bulk glass of the same composition. By means of molecular dynamics simulations of binary model glasses (Cu-Zr) we could show that glass-glass interfaces are characterized by a modified local order and an excess volume similar to that found in shear bands induced by plastic deformation. Experimentally studied Fe-Sc glasses exhibit clearly modified mechanical and magnetic properties and show a nanosized structural elements in the microstructure. It is the main goal of this research project to gain a consistent picture of the microstructural features of nanoglasses. Our primary scientific objective is to understand the physical origin of the massive density fluctuations that are observed experimentally and to find reasons for the unexpected thermal stability of nanoglasses.. In particular, we will study the sintering mechanisms occurring during cold compaction by varying particle sizes, pressures and materials. Experimentally, we will extend our study by non-magnetic Pd-Si, which can also be described by classical molecular dynamics simulations, while electronic structure calculations of Fe-Sc in bicrystal geometry shall assist in quantifying the experimental findings.