Mingwei Chen (Extra SIMES Seminar)

Date(s) - Nov 20 2014
11:00 AM - 12:00 PM

Shasta Room, Bldg. 40, Room 361


Spatio-temporal correlation of disordered systems: the case study of metallic glasses

Mingwei Chen

WPI-AIMR, Tohoku University, Japan


Although periodic and symmetric objects are the favorite of human beings, the fact is that most matter in the universe is random and disordered. Understanding disordered systems has been one of the most challenging scientific issues of today. This talk will present the aspect of inherent correlation between structure and dynamics at different length scales in metallic glasses, a typical disordered system with individual atoms as basic constituents. The lack of long-range translational and rotational symmetry of metallic glasses renders it experimentally inaccessible to determine their atomic structure by conventional diffraction/imaging methods. To overcome this experimental difficulty, we recently developed an Angstrom-beam electron diffraction approach to probe local atomic configurations of amorphous matter using a ~ 0.4 nm near coherent electron beam. By utilizing the state-of-the-art technique, we experimentally revealed the pronounced short- and medium-range order, arising from strongly correlated atoms, in the disordered materials. We also provided compelling evidence that geometric frustration of the local order is the origins leading to the transition from local order to long-range disorder. Importantly, by manipulating the scope of the local ordering, the dynamic behavior of metallic glasses can be tailored, which paves a new way to design/develop new amorphous materials for engineering applications.