[BNC-all] Velimir Radmilovic, National Ctr. for Electron Microscopy, Lawrence Berkeley National Lab, Univ. of CA, Berkeley, 10/27/06 @ 3:30 PM, MSEE B012, (COARSENING KINETICS IN Al-Sc AND Al-Sc-Zr ALLOYS)

[Kathy Moore]

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
          
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