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MM: Metall- und Materialphysik
MM 36: Amorphous and Liquid Materials IV
MM 36.2: Vortrag
Donnerstag, 30. März 2006, 16:45–17:00, IFW B
Rheology of selected metallic glasses — •Andreas A. Kündig1, Thomas Schweizer2, and Jörg F. Löffler1 — 1Laboratory of Metal Physics and Technology, Swiss Federal Institute of Technology (ETH) Zürich, Wolfgang-Pauli-Str. 10, CH-8093 Zürich, Switzerland — 2Polymer Physics, ETH Zürich, CH-8093 Zürich, Switzerland
Metallic glasses exhibit a superplastic forming regime at temperatures above the glass transition temperature (Tg) and below the crystallization temperature (Tx). The formability in this range is limited by the onset of crystallization, which typically causes the characteristic properties of metallic glasses to deteriorate. In this work, the direct rheological parameters of selected low-temperature metallic glasses (Cu-, Mg-, and Au-based) were measured in parallel plate geometry. Using this technique, absolute values for the elastic modulus and the loss modulus as a function of the temperature are obtained, allowing us to compare formability in the different systems. Additionally, strain-rate sensitivity, dynamic viscosity and the onset of crystallization were measured to determine optimum forming parameters. The results are discussed with respect to more easily accessible estimates based on thermal values, such as the extension of the undercooled liquid regime Δ T (=Tx − Tg) or, normalized to the liquidus temperature (Tl), the value S = Δ T / (Tl − Tg).