Iridium alloys for space power (07/02/24)

2 minute read

Speaker and Affliation:

Prof. Easo George
University of Tennessee, USA


7th February, 2024 (Wednesday), 04.00 PM (India Standard Time)


KI VASU Auditorium, Dept. of Materials Engineering, IISc, Bangalore


Interplanetary spacecraft need onboard electric power that is reliable and stable over many years. Solar cells and fuel cells can be used for near-Earth missions but, for deep space missions, radioisotope thermoelectric generators (RTGs) remain the only viable option. Most recently, they have been used on board the two Mars rovers currently exploring its surface, and before that the New Horizons mission to Pluto and the Cassini mission to Saturn. After a brief review of different space power systems and their relative advantages and limitations, this talk will focus on the iridium alloy that is used to clad the plutonia fuel in RTGs. Iridium is an FCC metal with many desirable properties including a high melting point, and compatibility with both the oxide fuel and the graphite insulation at elevated temperatures. Its mechanical properties are strain rate sensitive, and influenced by grain size and trace levels of alloying elements, both of which are affected by processing. Alloying elements can be beneficial, harmful, or relatively benign and examples of each will be discussed. Throughout the talk, the underlying mechanisms responsible for the observed effects will be highlighted

About the Speaker

Easo George is Em. Prof. at the University of Tennessee and Apl. Prof. at the Ruhr-Universität Bochum (RUB) in Germany. Previously, he was the Governor’s Chair for advanced alloy theory and development at ORNL and UT (2017-2022), Professor of Materials Design and Director of the Center for Interface Dominated High Performance Materials at RUB (2014-2017), and distinguished scientist and leader of alloy behavior and design at ORNL (1987-2014). George’s interests include the physical metallurgy and mechanical behavior of high-entropy alloys and intermetallics, refractory alloys for space power, and size effects on mechanical behavior. His honors and awards include: Clarivate (Web of Science) Highly Cited Researcher (2021); Energy Secretary’s Honors Award (2022) and NASA Award (1999) for contributions to Mars Perseverance Rover and Cassini Mission to Saturn, respectively; Eminent Scholar Visitation Award, University of New South Wales, Sydney (2019); Invitation Fellowship for Senior Scientists, Japan Society for the Promotion of Science (2013); Elsevier award for top cited paper in Scripta Materialia during 2007-2011; TMS Fellow (2010); Humboldt-Forschungspreis, Alexander von Humboldt Foundation (2000); ranked 8th in the world in total citations and 5th in citations per paper by ISI (now Web of Science/Clarivate) among highly cited authors in materials science and engineering during 1990-1994.