IMX/IPHYS Talks - Designing Resilience at Materials Interfaces for Extreme Tribological Demands

As engineering systems evolve to operate in extreme environments—from aerospace and marine to nuclear, microelectronic, and biomedical applications—materials are required to perform under increasingly severe, far-from-equilibrium conditions. Among the most challenging are aqueous and high-temperature oxidative environments, where traditional materials often fail due to the combined effects of tribological and environmental stresses. In this talk, I will share how resilience can be engineered directly into material surfaces to overcome these extreme tribological challenges.
In aqueous conditions, the dual challenge of mechanical wear and corrosive attack complicates the development of high-performance alloys. A classic example is aluminum (Al), whose passive film offers corrosion resistance but is easily disrupted under tribological stress, leading to accelerated material loss. I will show how alloying Al with excess manganese (Mn) enhances both corrosion and wear resistance. Remarkably, Mn improves passivity not by forming oxides itself, but by promoting the formation of a denser, more protective Al-oxide film through selective dissolution and interface modification. This design strategy offers a pathway to break the conventional trade-off between strength and corrosion resistance.
At high temperatures above 600 °C, tribological demands shift toward preventing softening, oxidation, and lubricant failure. I will present our recent advances showing that additively-manufactured Inconel superalloys can sustain remarkably low coefficients of friction (COF 0.10–0.32) at temperatures up to 900 °C. This performance is enabled by the in-situ formation of spinel-based oxides, which act as robust self-lubricating layers. These spinels, with their low shear strength and favorable thermodynamic properties, outperform conventional lubricants such as 2D layered solids and Magnéli phases. Our integrated approach reveals the mechanistic origins of this behavior and points to a new direction in high-temperature tribological materials design.
These findings demonstrate how reimagining surface structure and property can lead to exceptional tribological performance in extreme environments. I will conclude by outlining a few future research directions that explore where this work is headed—and how it could shape the next generation of resilient, intelligent materials.

Bio: Dr. Wenjun (Rebecca) Cai is an Associate Professor in the Department of Materials Science and Engineering at Virginia Tech. Before joining Virginia Tech in August 2018, she served as a faculty member in the Department of Mechanical Engineering at the University of South Florida (2012–2018). Her research focuses on uncovering the processing–structure–property relationships of metals and coatings under extreme tribological conditions, integrating experimental methods, analytical modeling, and computational simulations. Dr. Cai earned her B.S. in Materials Science and Engineering from Fudan University in 2005 and her Ph.D. from the University of Illinois at Urbana-Champaign (UIUC) in 2010. She conducted postdoctoral research at the Massachusetts Institute of Technology from 2010 to 2012. Her contributions have been recognized with numerous awards, including the Racheff-Intel Award for Outstanding Graduate Research at UIUC (2010), the National Science Foundation CAREER Award (2015), the Outstanding Faculty Award from USF (2016), and the TMS Young Leaders Professional Development Award (2017). Most recently, she was named to the College of Engineering Dean’s List for Teaching Excellence at Virginia Tech for 2023–2024.