Geometric structure of Bergman clusters related to bulk amorphous alloys and quasicrystals |
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| Authors: | Xiao-Dong Wang Min Qi Patricia A Thiel Chuang Dong |
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| Institution: | 1. State Key Laboratory for Materials Modification and Department of Materials Engineering , Dalian University of Technology , Dalian 116024, PR China;2. Ames Laboratory and Department of Chemistry , Iowa State University , Ames, Iowa 50011, USA;3. State Key Laboratory for Materials Modification and Department of Materials Engineering , Dalian University of Technology , Dalian 116024, PR China;4. Ames Laboratory and Department of Chemistry , Iowa State University , Ames, Iowa 50011, USA |
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| Abstract: | The fcc Zr2Ni- and MgCu2-type phases, being primary crystalline products of certain amorphous alloys with high glass-forming ability, should provide local structural information about the related amorphous alloys. The present paper gives a detailed analysis of the common structural features of these two fcc phases. They are both built from a similar building block consisting of tetrahedrally packed icosahedra. They also have shelled local structures similar to the first two shells of the Bergman-type clusters found in many icosahedral quasicrystals. Therefore the Bergman-type clusters probably play an important role in amorphous phase formation. Because of topological close packing inside dual-intergrown icosahedra, characteristic of Bergman clusters, the atomic radius ratios of the first- and second-shell atoms with respect to the central atom are nearly equal and fall in the range 1.1–1.2. |
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