“Origins of Excellent Corrosion and Passivation Attributes of Multi-Principal Element Alloys in Aqueous Solutions“
Multi-principal element alloys (MPEAs) offer the possibility of many degrees of freedom in the choice of alloying elements to produce either single phase solid solutions or more complex multiphase microstructures. Large ranges of material properties have been observed for MPEAs and mastery of the selection of elements and their compositions can enable novel combinations of properties not seen in traditional alloys. From the aqueous corrosion perspective, optimization of phase stability, control of heterogeneities, passive film identity and its protectiveness, as well as substrate properties such as metal-metal bond strength and activation energy associated with dissolution, are controlling factors to consider governed by alloy composition and structure. These factors can favor protective passive films that mediate the electrochemical reactions controlling spontaneous corrosion. The quest for superior properties based on well-informed element choice is suggested as a path forward guiding MPEA formulations for corrosion performance. However, gaps in fundamental knowledge exist regarding (a) the specific functions of each element towards passivation and resistance to dissolution, (b) the behavior of elements in unusual combinations, and (c) the possible formation of complex multi-element protective oxides. These issues currently hold back progress in optimization of corrosion properties in this class of materials.
John R. Scully is the Charles Henderson Endowed Chaired Professor of Materials Science and Engineering, the Co-director of the Center for Electrochemical Science and Engineering and MSE Department Chair at the University of Virginia. He has been devoted to research and education in corrosion focusing on the effects of material structure, composition, and environment on corrosion of both novel advanced materials, coatings, and legacy materials. Electrochemistry, surface science and material science are frequently integrated in his research to advance fundamental understanding and engineering of corrosion issues. He has co-authored numerous archival papers, proceedings articles and books or book chapters. John Scully is a Fellow of the Electrochemical Society, the National Association of Corrosion Engineers, The British Corrosion Institute, and the American Society for Metals. He received the A.B. Campbell, H.H. Uhlig, W.R. Whitney, and T.J. Hull Awards from NACE, the H.H. Uhlig award from the Electrochemical Society, the T.P. Hoar and U.R. Evans Awards from the British Corrosion Institute, the Lee Hsun Lecture Award from the Chinese National Academy of Science and the Francis La Que Award from ASTM. He chaired the 2004 Gordon Research Conference on Aqueous Corrosion and served on the editorial boards of Materials and Corrosion, Metallurgical Transactions and CORROSION. He is the Chief Technical Editor of CORROSION, The Journal of Science and Engineering. He has made key contributions to several national academy, defense science task force, and international corrosion reviews including studies on Reliability of Oil and Gas Bolting Materials, Corrosion Education, Research Opportunities in Corrosion Science and Engineering, Corrosion Control and Airborne Refueling, as well as reviews of U.S., U.K., Canadian and Swedish plans to ensure the integrity of spent nuclear fuel containers.