A Study of Grain Boundary Structure and Transformations Utilizing the Faceting Phenomenon in a Cooper-Bismuth Alloy

本研究以掺铋铜中由于溶质偏析而形成的原子平坦晶界小面为模型系统，研究了双组分合金晶界成分与组织的关系以及组织的演变。主要的实验工具是常规的和高分辨率的电子显微镜(HREM)。这种方法是针对一对特定的取向不同的颗粒对，识别相邻两个颗粒中每一个小平面的晶体取向，然后用高分辨电子显微镜确定铋原子在小平面中的位置。将这些结果与原子计算进行了比较。研究了刻面类型随时间和退火温度的变化。这项研究提供了有关晶界偏析的原子尺度结构和化学成分的重要信息。晶界在决定多晶材料的物理性能方面起着重要作用。

This research employs the atomically flat grain-boundary facets which form as the result of solute segregation in bismuth-doped copper as a model system with which to study the relationship between grain boundary composition and structure and the evolution of structure in a two component alloy. The principal experimental tools are conventional and high-resolution transmission electron microscopy (HREM). The approach is to identify crystallographic orientations of the facet planes in each of two abutting grains for a grain pair of specific misorientation, and then determine the location of the bismuth atoms in the facets by HREM. These results are compared to atomistic calculations. Evolution of facet types is examined as a function of time and annealing temperature. %%% This research provides important information about the atomic-scale structure and chemistry of segregation at grain boundaries. Grain boundaries play an important role in determining the physical properties of polycrystalline materials.