Rensselaer Polytechnic Institute
Dept. of Materials Science & Engineering
Understanding Structure and Fracture Behavior of Glass from Its Elastic Response
Location: EB1 Room 1011
Friday, October 17th 2014 - 11:00 am
Characterizing the disordered structure of glass at the microscopic level remains a grand challenge. On the macroscopic level, glass is structurally homogenous and isotropic; only two independent elastic constants are needed to characterize its elasticity. Elastic constants including the Poisson's ratio of glass are simple to define and easy to measure, and directly related to the interatomic forces and potentials, embodying its local structure and bonding information. Our in-situ light scattering studies show that changes in elastic moduli of glass in response to external stimuli such as high temperature, high pressure or high strain can be used as a probe to gain insights into the atomic level structure of glass. We use elastic moduli and their dependence on temperature, pressure, and strain as critical inputs for developing and validating computer models of glasses with accurate short- and long-range interactions. These reliable computer models allow us to complement experiments to obtain detailed structure-property relationships, and to study the large-scale deformation of glasses. Our molecular dynamics simulations show that the failure mode of glass correlates strongly with the Poisson's ratio. A brittle-to-ductile transition was observed with increasing Poisson's ratio in all three families of glasses (silica, amorphous silicon and model metallic glasses) we studied. Therefore, the far-from-equilibrium fracture behavior of glass can be understood from its near-equilibrium elastic response and the Poisson's ratio may be set as an optimization target to make tougher glasses.
Dr. Liping Huang is an Associate Professor of Materials Science and Engineering at Rensselaer Polytechnic Institute (RPI) in Troy, New York, USA. She obtained her Ph.D. degree from the University of Illinois at Urbana-Champaign. After several years of postdoctoral research experience at the University of Michigan and North Carolina State University, she joined RPI in 2008. Her primary research interest is to investigate the structure-property relationships at the atomic level in amorphous materials by using a combination of in situ light scattering techniques and multi-scale computer simulation methods. Among other awards, she was honored with the Norbert J. Kreidl Award from the Glass and Optical Materials Division in the American Ceramic Society in 2003. In 2009, she was a recipient of the Young Investigator Award from the Defense Treat Reduction Agency in the US Department of Defense. In 2013, she won the NSF CAREER award from the Ceramics Program, which provides a five-year grant to support her research on damage resistant glasses.