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.

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.