Prof. Omar Salim Es-said
Loyola Marymount University, USA
Title: Effect of Long-Term Elevated Temperatures on Mechanical Properties of AlSi10Mg
Abstract:
In this study, specimens of AlSi10Mg fabricated by
laser-powder bed fusion were exposed to 200°C, 220°C, 240°C, 260°C, 275°C, and
300°C for various times to characterize the changes in mechanical properties
over time. The duration of each isothermal treatment was varied from 15 minutes
to 1000 hours; one group of specimens was left in the “As-printed” condition as
a control. The resulting microstructure and mechanical properties were
characterized. Elastic modulus, percent elongation, 0.2% offset yield strength,
ultimate tensile strength, and hardness were measured and compared. The
morphology of the silicon-rich phase was observed at several time and
temperature conditions under magnification using scanning electron microscopy.
The strength and hardness decreased while the elongation increased 1) with increasing
time at a given temperature and 2) with increasing temperature for any given
time of exposure. The properties never reached a stable value for the durations
of the exposures in this study, as indicated by the change in measurements
after 300 and 1000 hours exposure. The effects of time and temperature on
mechanical properties is shown to be modeled well with the Larson-Miller model.
The microstructure changes from having a fine network of silicon-rich
precipitates to a coarse, equiaxed silicon precipitates with increased temperature
of exposure.
Keywords: AlSi10Mg, Long term
elevated temperature, Tensile properties, microstructure.
Biography:
Omar S. Es-Said is a professor in the Mechanical Engineering
Department at Loyola Marymount University in Los Angeles, California. He was
hired as an assistant professor from 1985-1992, associate professor from
1992-1998, and full professor from 1998-present. He received his B.S. degree in
physics and his M.S. degree in solid state physics from The American University
in Cairo. He received his PhD in Metallurgical Engineering and Materials
Science from the University of Kentucky, Lexington in 1985. His current
research interests include metallic processing, modeling, experimental
techniques, characterization of additively manufactured alloys and failure
analysis. He published over 300 papers, which included refereed journal
articles, conference proceedings, industrial reports, and Department of Defense
(DoD) reports. He has been an associate editor from 2008-present for the
American Society of Materials’ (ASM) Journal of Materials Engineering and
Performance (JMEP). He has been a key reader for the Metallurgical Transactions
A Journal from 2004-2015. He has been on the editorial board of the Engineering
Failure Analysis Journal from 2003-present. He received several awards: The
Society of Automotive Engineers (SAE), Teetor Award in 1994, until the Elmer L.
Hann Award from The Society of Naval Architects and Marine Engineers in 2011.
He received several grants for research funds and research equipment from the
National Science Foundation (NSF), NASA, Boeing Cooperation, and the Navy for a
total of over $3.2 million dollars. He was a consultant for the Navy from
1994-2018. He was hired as a Distinguished Summer Faculty Fellow at The Navy
Facilities Engineering Services Center (NFESC) in the summers of 2010-2018. He
became an American Society of Materials (ASM) Fellow in 2005. He was an invited
speaker in many conferences and universities including: Cambridge University,
The American University in Cairo, and Paris 8 University.