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