Structural study on quasicrystals and their approximants in the Al-Ni-Co alloy system, by means of anomalous X-ray scattering

Al-Ni-Co十方相由于在十方准晶的几种调制方式中，呈现出高度有序的或具有超晶格反射的几种不同类型的衍射图，以及一些晶型近似而备受关注。为了揭示这些十方准晶的结构，人们用电子衍射分析、高分辨电子显微镜(HRTEM)和大角度环形探测器暗场扫描电子显微镜(HAERDF-STEM)进行了大量的研究。然而，前人对单个十方准晶进行了研究，还没有对所有Al-Ni-Co十方准晶的结构进行系统的解释。本研究项目对Al&lt；72.5&gt；Ni_&lt；17&gt；Co_&lt；20.5&gt；合金中发现的一种在950℃退火热处理后的近似晶态进行了精确的结构分析。这种W-(AlCoNi)相的结构使我们能够讨论STR…更详细地描述了Al-Ni-Co十方准晶的结构。这些研究成果可以作为考虑准晶和相关近似晶体的最重要的结构信息之一，并邀请首席研究员参加2001年国际准晶会议。本研究项目发展了相对较新的单晶反常X射线散射技术，它促使我们了解合金样品中特定元素的精细结构。这一新的分析工具成功地表征了铜在Al-Cu-Fe近似相中的分布，并使我们了解了铜在准晶相关近似相形成中的结构作用。本课题组还对具有大的二十面体原子簇的立方相的结构进行了系统的研究。所获得的结果在准晶国际研讨会上作为主要讲座进行了演示。较少

The Al-Ni-Co decagonal phase has received much attention, because, of several modulations of decagonal quasicrystals, showing highly-ordered diffraction patterns or several different type of diffraction patterns with super-lattice reflections, and some crystalline approximants. In order to reveal the structures of these decagonal quasicrystals, many studies have been made by electron diffraction analysis, high-resolution transmission electron microscopy (HRTEM) and high-angle annular detector dark-field scanning transmission electron microscopy (HAERDF-STEM). However, previous studies have been made on individual decagonal quasicrystals, and no systematic interpretation on the structures of all the Al-Ni-Co decagonal quasicrystals has been performed. This research project has performed precise structural analysis of a crystalline approximant, which is found in alloy around Al_<72.5>Ni_<17>Co_<20.5>, annealed at 950℃. The structure of this W-(AlCoNi) phase, enables us to discuss the str … More uctures of the Al-Ni-Co decagonal quasicrystals in detail. These research results can be referred as one of the most important structural information considering the quasicrystals and related approximant crystals and the head investigator was invited to International Conference of Quasicrystals 2001.The present research project developed the relatively new technique of single crystal anomalous X-ray scattering technique, which prompts us to know fine structure around a specific element in an alloy sample. This, new analytical tool succeeded to characterize the distribution of Cu in the Al-Cu-Fe approximant phase and allowed us to understand the structural role for Cu for the formation of approximant phase related to quasicrystals.The present research group has also performed the systematic research with respect to structures of cubic approximant phase with large icosahedarl atom clusters. The obtained results were demonstrated in the International Workshop for Quasicrystals as a key lecture. Less