How Grain Boundary Segregation Enables 3D Printing of Bulk Nanostructured Metals
Professor Christopher A. Schuh, 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 even at room temperature, and the associated property benefits decline over time in service. In this talk, our efforts to design stable nanocrystalline alloys will be described. We rely on selective alloying as a method to lower the energy of grain boundaries, which can bring a nanocrystalline structure closer to equilibrium. This talk will highlight the path from theory, to proof-of-concept laboratory demonstration, to scale-up and commercialization of such alloys. Beginning from early successes with nanocrystalline alloy coatings, the talk will build to address current opportunities in bulk net-shape products and additive manufacturing.