Attached is Materials Engr next seminar speaker's abstract and bio. Please post and forward to your faculty and grad stdts. Thanks! Kathy Moore ----------------------------------------------- Laura K.(Kathy) Moore, Faculty Assistant Purdue University, School of Materials Engineering 501 Northwestern Avenue - MSEE 150 West Lafayette, IN 47907-2044 (765)494-4100 (765)494-1204 (FAX) MATERIALS SCIENCE AND ENGINEERING SEMINAR COARSENING KINETICS IN Al-Sc AND Al-Sc-Zr ALLOYS by Velimir Radmilovic National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA Abstract We have investigated the coarsening kinetics of Al3X-type phases in binary Al-Sc and ternary Al-Sc-Zr alloys. Addition of Zr to binary Al-Sc is known to enhance the alloy's recrystallization resistance and hardness. This work uses transmission electron microscopy to examine the effect of Zr additions on the precipitation kinetics and morphology of Al3(Sc,Zr) precipitates. Since Zr is soluble in Al3Sc, which is isostructural with Al3Zr, it is usually assumed that the precipitates in ternary Al-Sc-Zr are Al3(Sc,Zr). In this study, we find coherent precipitates with L12 structure and highly anisotropic shapes that consist of a core of Al3Sc surrounded by a thin shell of Al3Zr. The addition of Zr strongly modifies the size of the L12 precipitates during aging by impeding the coarsening kinetics. The activation energy for coarsening was measured to be ~230kJ/mol for both Al-Sc and Al-Sc-Zr alloys. The reduced coarsening rate in the ternary alloy is apparently related to the interfacial energy between the Al matrix and the Al3(Sc,Zr) precipitate. Date: Friday, October 27, 2006 Time: 3:30 - refreshments 3:45 - Seminar Place: MSEE B012 Short Bio - Velimir Radmilovic Dr. Radmilovic is a leading expert in the area of precipitation phenomena in aluminum alloy systems, with a particular emphasis on characterization using advanced analytical techniques. He obtained his Ph.D. in Physical Metallurgy in 1985, and subsequently trained with Prof. Gareth Thomas at the Lawrence Berkeley Laboratory. Thereafter he returned to Belgrade to become both a Professor and Department Head at the University of Belgrade, and has held visiting professorships at both UC Berkeley and the University of Pittsburgh. Presently, he is a Principal Investigator in the Materials Sciences Division and Staff Scientist at the National Center for Electron Microscopy at LBNL, where he leads the analytical microscopy efforts in the facility. PURDUE MSE