非平衡Al-Ni-Co合金中十次准晶的结构分析与表征

罗 颖,张月颖,刘翠秀*,刘林林,孙 威

非平衡Al-Ni-Co合金中十次准晶的结构分析与表征

罗 颖,张月颖,刘翠秀*,刘林林,孙 威

(北京工业大学材料与制造学部,北京 100124)

     本文主要利用原子分辨的高角环形暗场扫描透射电镜(HAADF-STEM)成像技术与选区电子衍射(SAED)技术,对非平衡Al-Ni-Co合金中十次准晶的结构进行了表征,结果表明其基本结构单元除了包含平衡态Al-Ni-Co十次准晶超结构变体中的五次对称原子团,还具有非平衡Al-Ni-Co十次准晶中独有的对称性破缺原子团,是一种新的Al-Ni-Co十次准晶超结构变体。通过用不同的拼砌来描述该准晶结构,发现在急冷状态下对称性破缺原子团的存在导致了相子缺陷的产生,从而破坏了该准晶的长程有序性。通过安曼线和特征相子分析发现,该观察区域内安曼线分布无明显差异,特征相子分布无明显变化,反映出该区域准晶相的线性相子应变是单一的,这与平衡状态下十次准晶相结构特征完全不同。

关键词   Al-Ni-Co;非平衡;拼砌结构;长程生长结构;HAADF-STEM

中图分类号:TG146.2;TG115.21+5.3;O753+.3;O77+文献标识码:A   doi:10.3969/j.issn.1000-6281.2024.02.005

 

Structural characterization of decagonal quasicrystals in non-equilibrium Al-Ni-Co alloys

LUO Ying,ZHANG Yue-ying,LIU Cui-xiu *,LIU Lin-Lin,SUN Wei

(Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China)

Abstract   In this paper, the atomic resolved HAADF-STEM imaging technique andSAED were used to characterize the structure of decagonal quasicrystals in non-equilibrium Al-Ni-Co alloys. The results showed that the basic structural unit was composed of a five-fold symmetry atomic cluster in an equilibrium Al-Ni-Co decagonal superstructure variant and a unique symmetry-breaking atomic cluster in a non-equilibrium Al-Ni-Co decagonal quasicrystal. This decagonal quasicrystal presented a new Al-Ni-Co superstructure variant. The existence of the symmetry-broken atomic cluster in the quench cooling state led to the generation of phase defects, which destroyed the long-range order of the quasicrystal. There was no obvious difference in the distribution of Amman lines and the characteristic phason distribution in the observation region, reflecting that the linear phason strain of the quasicrystal phase in this region was homogeneous, completely different from the structure characteristics of the decagonal quasicrystal phase in the equilibrium state.

Keywords    Al-Ni-Co; non-equilibrium; tiling structure; long growth structure; HAADF-STEM

 

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