Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.17: Poster

Montag, 11. März 2013, 18:00–20:00, Poster E

Relationship between enthalpy relaxation and shear modulus relaxation below and above the glass transition of metallic glasses — •Yuriy Mitrofanov^1,2, Andrey Makarov³, Vitaly Khonik³, Andrew Granato⁴, Dave Joncich⁴, and Svetlana Khonik⁵ — ¹Institute of Materials Physics, University of Münster, Münster, Germany — ²Department of Solid State Physics, State Technical University, Voronezh, Russia — ³Department of General Physics, State Pedagogical University, Voronezh, Russia — ⁴Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA — ⁵Centre for Joint Research, State University, Voronezh, Russia

Despite decades-long investigations of the enthalpy relaxation in metallic glasses, its nature remains unclear. To understand the nature of the enthalpy relaxation near Tg, we used an approach, that is based on the interstitialcy theory. We derived a simple and testable expression for the heat flow (enthalpy relaxation rate) occurring upon heating of the glass at a constant rate. This heat flow is mostly determined by the shear moduli of the glass and the parent crystal. The shear modulus of the glass is defined by the concentration of frozen-in interstitialcy-like defects (atomic configurations with two atoms sharing the same potential well). The relaxation law describes both, the exothermic heat flow below Tg and endothermal heat flow above Tg and reflects a generic connection between the elastic properties of the glass and the parent crystal. An extensive check of the derived heat flow law for temperatures near the glass transition showed good agreement with the experiments performed on two Pd-based metallic glasses.