APL Colloquium

May 22, 2009

Colloquium Topic: Complexions: New States of Matter at Interfaces

Recent theoretical and experimental work has revealed the existence of grain boundary "complexions" in a wide range of ceramic and metal systems. Complexions are equilibrium interface 'phases' that have associated thermodynamic properties such as excess volume, entropy and adsorption. Through control of the complexions, the grain boundary transport rate and hence the microstructure and material performance can be engineered towards a given application requirement. This presentation will summarize the current understanding and future prospects in this exciting new field of interface science and engineering. The role of grain boundary complexions in controlling abnormal grain growth will be given special consideration. Many of the details remain unresolved, which will be a good topic for discussion.

Colloquium Speaker: Martin P. Harmer

Martin P. Harmer is Director of the Center for Advanced Materials and Nanotechnology at Lehigh University, and has over 25 years of research experience in the field of ceramic science and materials engineering. He has worked extensively on the mechanisms of sintering and grain growth and in the kinetic engineering of transport rate processes in ceramic materials. Most recently he has advanced the process of solid state single crystal conversion. His group has also addressed fundamental scientific problems in structural ceramics, including identifying the strengthening mechanism in alumina–silicon carbide ceramic nanocomposites and the mechanism of creep inhibition in rare-earth doped aluminas. In addition, he has made significant contributions in electronic ceramics. He has published more than 200 papers in peer reviewed scientific journals. He has received numerous honors and awards including an honorary Doctor of Science degree, Humboldt Prize, Fellow of the American Ceramic Society and is one of a select few of ISI most highly cited researchers in the United States. He is an internationally recognized accomplished research scientist. He has served as the Principal Investigator of DARPA, ONR, AFOSR, and NSF government funded programs, as well as state and industry funded projects.