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M: Metallphysik

M 4: Quasikristalle

M 4.1: Vortrag

Montag, 27. März 2000, 15:15–15:30, H6

Composition and precipitation behavior of icosahedral quasicrystals in Al-Pd-Mn — •Benjamin Grushko — Forschungszentrum Juelich GmbH, D-52425 Juelich

Refinement of the Al-Pd-Mn phase diagram [1] revealed that the composition of the icosahedral phase (I-APM) shifts to lower Mn at lower temperatures. This is argued that I-APM (stable or metastable) forms in the whole range between about Al78Mn22 and Al70Pd25-5Mn5. Accordingly, the basic composition of I-APM should be binary. Several structural imperfections of the usual I-APM sample material are associated with its supersaturation at ambient temperatures. Precipitation of secondary phases is demonstrated in the "standard" single quasicrystals produced by the Czochralski technique. The relation of these observations to the diffuse scattering observed in the diffractograms of I-APM is discussed.

[1] B. Grushko, M. Yurechko and N. Tamura, J. Alloys Comp. 290 (1999) 164.