Hamburg 2001 – wissenschaftliches Programm

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M: Metallphysik

M 21: Symposium Unterkühlte Metallschmelzen VII

M 21.5: Fachvortrag

Dienstag, 27. März 2001, 12:45–13:00, S12

Mechanical spectroscopy of Zr-based bulk metallic glasses — •Roberto Scarfone and Hans-Rainer Sinning — Technische Universität, Institut für Werkstoffe, 38106 Braunschweig

Mechanical spectroscopy combined with the use of hydrogen as a probe has been chosen to investigate firstly the phase transformations, then the structural affinities and differences in various Zr-Ti-Cu-Ni-Be and Zr-Cu-(Ni)-Al alloys. The change of eigenfrequency of a clamped-free vibrating reed as function of temperature showed peculiar features characterising, for example, the phase separation of Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 or the formation of metastable quasicrystalline Zr_69.5Cu₁₂Ni₁₁Al_7.5. The developing of hydrogen induced damping spectra, for H concentrations in the range from 0.003 to 0.3 H/M, was studied in structurally relaxed glasses as well as in quasicrystals and crystallised structures. No significative difference could be found in the shape of the internal friction peaks for the amorphous and icosahedral states, meaning that a similar short range order dominates in both phases. Due to such similarity, the nucleation of quasicrystals from the glassy state is energetically favourable and plays an important role in the destabilisation of the undercooled melt.