Correlating the atomisitic nature of grain boundary phase transformations to their macroscopic kinetic properties

本建议的目的是关联的原子起源的金属晶界上的输运性质的影响的结构转变。其目标是建立一个基本的理解温度引起的纯金属晶界的晶界相变，以及那些由杂质偏析引起的，以及它们对界面性能的直接影响。晶界的结构和过渡将探索在原子尺度上的像差校正的透射电子显微镜（TEM）和它们的宏观输运性质将探测示踪剂扩散实验。实验结果将系统地支持选定的接口的结构和扩散的原子模拟。在Cu-Ag，Cu-Co和Cu-Zr系统中，将探索偏析诱导的晶界转变及其对动力学性质的影响。定义的[001]倾斜晶界将通过本体双晶体生长获得，允许根据需要定制晶粒取向差和晶界倾斜度。这也使得从原子水平到微米长度尺度的尺度桥接表征成为可能。所获得的Cu晶界将在受控条件下用Ag、Co和Zr掺杂，并且先进的TEM解析它们的温度依赖性结构、偏析和转变。相同的晶界探测示踪剂扩散实验，以确定其动力学性质平行和垂直于倾斜轴。此外，还将探讨晶界倾斜偏差对晶界转变及其输运性质的影响，以全面了解晶界转变对界面性质的影响。

The present proposal aims to correlate the atomistic origins of structural transformations at metallic grain boundaries with their impact on the transport properties. The goal is to establish a fundamental understanding of temperature-induced grain boundary phase transformations in pure metallic grain boundaries, as well as those induced by impurity segregation, and their direct impact on interfacial properties. The structure and transitions of grain boundaries will be explored at the atomic scale by aberration-corrected transmission electron microscopy (TEM) and their macroscopic transport properties will be probed by tracer diffusion experiments. The experimental results will systematically be supported by atomistic simulations of structure and diffusion of selected interfaces. Segregation-induced grain boundary transitions and their effect on the kinetic properties will be explored in the systems Cu-Ag, Cu-Co and Cu-Zr. Defined [001] tilt grain boundaries will be obtained by bulk bi-crystal growth, allowing to tailor grain misorientation and grain boundary inclination on demand. This also enables the scale bridging characterization from the atomic level to µm length-scales. The obtained Cu grain boundaries will be doped under controlled conditions with Ag, Co and Zr and advanced TEM resolves their temperature dependent structure, segregation and transitions. The same grain boundaries are probed by tracer diffusion experiments to determine their kinetic properties parallel and perpendicular to the tilt axis. Furthermore, the impact of deviations in grain boundary inclination on grain boundary transitions and their transport properties will also be explored to establish a holistic understanding of the impact of grain boundary transformations on interfacial properties.