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M: Metallphysik
M 9: Symposium Complex Metallic Alloys II
M 9.5: Vortrag
Freitag, 4. März 2005, 16:15–16:30, TU H1058
Surfaces of Al-rich complex metallic alloys — •Vincent Fournée1, Amy Ross2, Tom Lograsso2, Jack Barrow2, Masahiko Shimoda3, An-Pang Tsai3, and Patricia Thiel2 — 1LSG2M, CNRS-UMR7584, Ecole des Mines, Parc de Saurupt, 54042 Nancy, France — 2Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA — 3NIMS, 1-2-1 Sengen, Tsukuba-shi, Ibaraki 305-0047 Japan
Understanding the structure and physical behaviour of complex metallic alloy surfaces is of key importance. Up to now, most studies have been focused on the surface structure of Al-rich quasiperiodic alloys. It is found that the surface is formed at dense Al-rich layers of the bulk structure, with no reconstruction. This result is rather surprising as even for simpler systems like periodic bimetallic alloys, surface truncation of the bulk structure can give rise to atomic and chemical rearrangements, including surface relaxation, modification of the bulk periodicity (reconstruction) or the chemical composition (surface segregation). Here, we have investigated the surface structure of some related periodic alloy phases, namely the xsi-AlPdMn approximant, which is an orthorhombic crystal with a large unit cell. The surface perpendicular to its pseudo ten-fold axis was investigated by STM, LEED and XPD. The surface structure can also be interpreted as bulk-terminated, corresponding to dense Al-rich layers of the bulk structure. Similarities and differences between the quasicrystal and its periodic approximant will be outlined.