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M: Metallphysik

M 20: Symposium Unterkühlte Metallschmelzen VI

M 20.4: Fachvortrag

Tuesday, March 27, 2001, 11:00–11:15, S12

Weakening of Shear Bonds in Supersaturated Solid Solutions — •F. Jurányi¹, J.- B. Suck¹, and O. A. Petrenko² — ¹TU-Chemnitz, Institute of Physics, Materials Research and Liquids, 09107 Chemnitz, Germany — ²ISIS-Facility, RAL, Chilton, Didcot, Ox11 0QX, UK

Reducing diffusion during the production process, e.g. by

low energy ball milling, supersaturated solid solutions can

be formed in a certain concentration region. Supersaturation,

similar to superheating, weakens the bonds in the host matrix.

We have used neutron inelastic scattering at the thermal

neutron time-of-flight spectrometer MARI at the spallation

source ISIS (UK) to investigate the influence of supersaturation

of Al in Zr on the atomic dynamics. The Zr(100-x)Al(x) system

can be driven by supersaturation to an order-disorder

transition, resulting in an amorphous solid. The investigated

samples cover the hole range of interest: stable (x=5) and

supersaturated (x=10) solid solutions and the amorphous (x=20)

one. The results of our experiments show that increasing

supersaturation affects primarily the low energy dynamics:

an enhancement of the vibrational density of states in the

low energy region, an excess specific heat and a lowering of

the Debye temperature. We interprete these results as being

due to an increasing weakening of the restoring forces of

the shear modes on progressing supersaturation.