MMAE Seminar - Dr. Maarten de Jong - Computational Design of Rhenium-replacement Alloys for Naval Applications
Armour College of Engineering's Mechanical, Materials & Aerospace Engineering Department will welcome Dr. Maarten de Jong on Monday, November 14th, to present his lecture, Computational Design of Rhenium-replacement Alloys for Naval Applications.
Abstract
Among the refractory metals, rhenium exhibits a unique combination of a high melting point, good ablation resistance, good high temperature strength and creep resistance, a high ductility at room temperature and the absence of a measured brittle-ductile transition. Unfortunately, Re is also exceptionally expensive (~10,000 $/kg) and its worldwide reserves and production are limited. Therefore, viable and cost-effective replacement strategies for rhenium as material for solid propellant rocket nozzles have clear future naval relevance.
This talk describes recent progress on the design of refractory rhenium-replacement alloys. Alloying strategies are outlined that increase the intrinsic ductility of rhenium on one hand, while decreasing the total material cost on the other hand. Further, it is shown how first-principles calculations have been employed in this work to rationalize the unique properties of rhenium. In particular, a new concept is introduced, now known as the "twin-boundary energy anomaly" that occurs for metals and alloy that have similar d-band fillings to rhenium. It is shown how these anomalously low twin energies for rhenium result in its high ductility and how these are structurally related to topologically close packed phases. Based on these new insights, several new replacement alloys are proposed and experimental evidence (TEM and EBSD) is presented to support the viability of those alloys.
Finally, if time permits, an overview will be presented of high-throughput algorithms and calculations that were performed as part of this work. This work has culminated in the development of the largest (open-source) databases in the world of elastic and piezoelectric properties, in addition to a state-of-the-art machine learning framework that can be used for efficiently designing new alloys with target properties in the future.
* The research is conducted in collaboration with Dr. Mark Asta (University of California, Berkeley) and Dr. Axel van de Walle (Brown University).
Biography
Dr. Maarten de Jong received his BS and MS degrees in Aerospace, Aeronautical and Astronautical Engineering from Delft University of Technology, the Netherlands, and his PhD in Materials Science and Engineering from University of California, Berkeley. Dr. de Jong is a former UC Berkeley graduate student and currently a materials engineer at SpaceX. His academic interests include working on the design of new materials with improved properties, employing modern simulation techniques involving quantum mechanics, elasticity theory, metallurgy and machine learning. His specializations include data-driven discovery and optimization of metallic alloys, semiconductors and piezoelectrics. His particular scientific interests are in the area of strength, elasticity, ductility, hardness and piezoelectricity of materials.