The Role of Interfacial "Phases" in Microstructural Development

ChEMS Seminar

Featuring Shen Dillon, Ph.D.
Postdoctoral Research Associate
Materials Research Science and Engineering Center
Carnegie Mellon University

Location:  Engineering Tower, Room 204

Abstract:
Interfaces and the movement of atoms within an interface play a crucial role in determining the processing, properties, transport, reactions, reliability, etc. of many materials. Unfortunately, the nature of interfaces is highly complex, and it has been a continual challenge to link material performance with the internal interface structure and associated atomic transport mechanisms.  The emerging insight is that interfaces, such as grain boundaries, may be treated as distinct thermodynamic phases called complexions.  A particular complexion may be thought of as a family of interfacial structures that exhibit common structural features and have similar properties.  Different interface complexions are shown to exhibit drastically different transport kinetics.  In particular, alumina is shown to exhibit up to 6 different grain boundary complexions.  Experimental results for relative interfacial energies shed new light on the role of additives in affecting microstructural development by influencing the stability of complexions.  These results suggest a new approach to selecting additives to influence microstructural development. They also provide new insight into some longstanding issues such as abnormal grain growth.

About the Speaker:
Shen Dillon, Ph.D., received his Ph.D. degree in materials science and engineering at Lehigh University, in 2007.  Currently, he is a postdoctoral research associate at the Materials Research Science and Engineering Center, Carnegie Mellon University, with Gregory Rohrer, Ph.D., establishing a quantitative relationship between grain boundary complexions and grain boundary character distribution.