MSE Seminar Series: Christopher Schuh
Friday, September 19, 2014
Room 2108, Chemical and Nuclear Engineering Bldg.
301 405 5240
Harder, Cheaper, Greener: the Design and Deployment of Alloy Coatings with Stabilized Nanocrystalline Structures
Danae and Vasilios Salapatas Associate Professor of Metallurgy
Head, Department of Materials Science and Engineering
Massachusetts Institute of Technology
When the grain size of a metal is refined to a scale on the order of just a few nanometers, its strength, hardness, wear resistance, and other properties improve in dramatic ways. There is therefore significant interest in designing and deploying such nanocrystalline alloys for structural applications. However, refining the grain structure is a struggle against equilibrium, and nanocrystalline materials are often quite unstable; the grains grow given time even at room temperature, and the associated property benefits decline over time in service. In this talk, our efforts to design a stable family of nanocrystalline alloys will be described. We rely on selective alloying as a method to lower the energy of grain boundaries, bringing the nanocrystalline structure closer to equilibrium. Using analytical thermodynamic mixing calculations and Monte Carlo simulations, we identify desirable alloying elements for a given base metal, and assess the relative stability of nanocrystalline structures against grain growth. We then transition these modeling principles to the laboratory, produce materials, and experimentally validate the modeling results. Finally, the talk will review the connection between theory, experiment, and engineering application, and describe a suite of commercial products based on this research.