Regensburg 1998 – wissenschaftliches Programm

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M: Metallphysik

M 25: Postersitzung, gemeinsam mit AM,DS,DF,TT,SY B

M 25.20: Poster

Donnerstag, 26. März 1998, 15:10–19:10, A (Sammelgeb"aude)

Phase transformations of Zr-based bulk metallic glasses studied by Mechanical Spectroscopy — •Roberto Scarfone and Hans-Rainer Sinning — Institut f"ur Werkstoffe der TU, Langer Kamp 8, 38106 Braunschweig

The devitrification of metallic glasses upon heating often proceeds over a series of intermediate, metastable transformations prior to final crystallization. Such metastable states are particularly interesting for bulk glass-formers where nucleation and growth of crystalline phases are effectively hindered. Here, the development of short-range order certainly plays an important role but is difficult to observe experimentally. It may be expected that some information can be obtained from Mechanical Hydrogen Spectroscopy, using H-induced internal friction spectra as a local structural probe.

As a first step towards this aim, we present vibrating-reed measurements of the changes of elastic modulus and internal friction during the devitrification sequences of Zr-Cu-Al(-Ni) and Zr-Ti-Cu-Ni-Be glasses, as well as some first, selected results on the development of hydrogen relaxation spectra. Characteristic hydrogen relaxation peaks are observed not only for purely amorphous or crystalline states but also in the range of phase separation in amorphous Zr-Ti-Cu-Ni-Be and for an intermediate, quasicrystalline state in Zr-Cu-Al(-Ni).

Gef"ordert im Rahmen des DFG-SPP "Unterk"uhlte Metallschmelzen."