When 3:30 PM - 4:30 PM Oct 13, 2016
Where GM Room, Lurie Engineering Building
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The 2016 Van Vlack Lecture Series: What are Glasses?: Atomic Organization and the Price of Non-Conformity


William L. Johnson
Ruben F. and Donna Mettler Professor of Engineering and Applied Science California Institute of Technology

As a simple liquid like molten gold is cooled below its melting point, its atoms undergo an abrupt crystallization transition, freezing into a regular periodic pattern with every atom in an identical local neighborhood. Suppose there are nonconforming atoms in the liquid – for example, silicon atoms dissolved in the gold— that prefer a different type of neighborhood. Too many non-conformists, and crystallization becomes frustrated. With crystallization avoided, the liquid still solidifies on cooling – it vitrifies. In the resulting glass, atoms are frozen in diverse and randomly varying neighborhoods. Due to inherent randomness, glasses differ from crystals in profound and often surprising ways. Johnson will describe selected scientific and practical consequences based on his experience in the developing and studying metallic glasses.

 

 

The Van Vlack Lecture Series was established in honor of L. H. Van Vlack, to provide a distinguished lecture series from the outstanding leaders in the field of Materials Science and Engineering