STRUCTURAL STUDY OF ICOSAHEDRAL AL65CU20TM15 (TM = FE, RU, AND OS) AND DECAGONAL AL75FE15NI10 ALLOYS BY ANOMALOUS X-RAY-SCATTERING

The structural study has been carried out in fully annealed quasi-crystalline Al65Cu20TM15 (TM = Fe, Ru and Os) and as-quenched decagonal Al75Fe15Ni10 alloys by anomalous x-ray scattering (AXS) and ordinary x-ray scattering techniques. The environmental radial distribution functions (RDFs) for Cu and Os atoms in the Al65Cu20Os15 alloy and those of Fe and Ni atoms in the Al75Fe15Ni10 alloy were determined and compared with the ordinary RDF which represents the average structure of the system. Environmental structures for Cu and Os atoms are quite different in the Al65Cu20Os15 alloy, which implies that Cu and Os atoms occupy different sites in icosahedral clusters. By comparing the ordinary RDFs of the three Al65Cu20TM15 (TM = Fe, Ru and Os) alloys, their fundamental atomic structure is found to be identical. The environmental RDFs for Fe and Ni atoms in the decagonal Al75Ni10Fe15 alloy resemble each other and also the ordinary RDF, which contrasts to the environmental RDFs for Cu and Os atoms in the Al65Cu20Os15 alloy. These results suggest that Ni and Fe atoms share their atomic sites in the decagonal Al75Fe15Ni10 structure.