MATERIALS SCIENCE AND ENGINEERING

DMSE Colloquia, Fall 2009

Tuesday, November 17, 2009 | 10:00 AM | 411 White Building

Influence of Condensed Bond Enthalpy on Metallic Glass Stability and Structure

Daniel B. Miracle

Materials and Manufacturing Directorate
Air Force Research Laboratory
Dayton, OH
U.S.A.

Abstract:

A range of phenomenological observations suggest a major chemical contribution to the stability of metallic glasses. A chemical contribution can be described by a number of approaches, including electronegativity, electronic structure, thermodynamic considerations, or atomistic calculations. Each of these approaches have previously been considered in limited detail. However, a general approach that gives a simple, physically-based, accurate description of the chemical contribution to metallic glass stability is still lacking. This work seeks to establish a connection between nearest neighbour interatomic bond enthalpies and glass-forming ability. An approach to determine bond enthalpies between like and unlike atom pairs in condensed structures will be described using classical thermodynamic concepts and available thermodynamic data, and the resulting bond enthalpies will be presented and discussed. The validity of this approach will be demonstrated by applying the condensed bond enthalpies to several practical problems in materials science. The number and type of atom bonds that are present in a metallic glass structure are estimated as a function of metallic glass constitution using the efficient cluster packing structural model. By combining these two analyses, we estimate the enthalpy associated with glass formation, and explore correlations between the relative magnitudes of bond enthalpies between like and unlike atom pairs and experimental measurements of glass-forming ability.

Coffee and doughnuts will be served from 9:30 AM.

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