Dresden 2003 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

M: Metallphysik

M 7: Quasikristalle I

M 7.4: Vortrag

Montag, 24. März 2003, 11:00–11:15, IFW B

Mechanical spectroscopy of amorphous-to-quasicrystalline transitions in rapidly quenched Ti-Zr-Ni(-Ag) alloys — •Hans-Rainer Sinning¹, Adrian Jianu², and Igor Golovin¹ — ¹Institut für Werkstoffe, TU Braunschweig, Langer Kamp 8, 38106 Braunschweig — ²Physik neuer Materialien, Univ. Rostock, August-Bebel-Str. 55, 18051 Rostock

Amorphous metals, if dominated by icosahedral short-range order, may be considered as a limiting case of a nano-quasicrystalline state with extremely small grain size (polycluster structure). Coarsening of such a state then means some type of amorphous-to-quasicrystalline transition, which can be studied experimentally using rapidly quenched Ti-Zr-Ni(-Ag) alloys [1].

In the present contribution, the Mechanical Spectroscopy technique (vibrating-reed, also combined with TEM, XRD, DSC) was applied to this subject, with the additional possibility of using absorbed hydrogen as a probe. The main effects of coarsening of nano-quasicrystalline microstructures are an irreversible increase of Young’s modulus, a partial reduction of the high-temperature damping background, and a narrowing of the Snoek-type relaxation peak of hydrogen. These coarsening effects may be discussed with respect to the increasing fraction of No-dqorderedNo-dq quasicrystals compared to No-dqdisorderedNo-dq intergranular regions, and additional modifications of local atomic order within both of these structural constituents.

[1] R. Nicula et al., Mat. Sci. Eng. A 294-296 (2000) 90