Interface-based design: A new frontier of alloy development

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The development of new alloys for lightweight materials and products can be significantly expedited by using integrated computational materials engineering (ICME) tools to accurately predict the microstructures which are the "fingerprints" that give a metal or alloy its unique properties. The interaction of alloying elements with migrating interfaces (grain boundaries and phase-interfaces) is a key aspect that determines microstructure evolution during thermo-mechanical processing. There is, however, a lack of thermodynamic and kinetic data for interfaces. Recent advances in atomic scale resolution characterization techniques and atomistic modelling have dramatically increased the potential to generate new knowledge on interfaces thereby enabling to revolutionize alloy design approaches. To develop a new interface-based design approach this projects brings together a group of Canada's leading computational material scientists with experimentalists at the Canadian Centre for Electron Microscopy. The approach will be illustrated for next generation advanced high-strength steels that will be critical in lightweight vehicle designs to reach the Canadian 2025 target level for fuel efficiency of an average vehicle (4.4 l/100 km). Compared to conventional automotive steels, these new steels will be based on non-traditional alloying strategies with for example increased levels of Mn (3-10 wt%), Si (1-3 wt%) and Al (2-6 wt%), which constitute a paradigm shift for steelmakers. Here, the austenite-ferrite transformation assumes a critical role as it is the key metallurgical tool to tailor the properties of these steels. Thus, the proposed work will emphasize the interaction of alloying elements with the austenite-ferrite interface in multi-component Fe-model alloys and steels. Supported by three leading Canadian steel producers (ArcelorMittal Dofasco, U.S. Steel Canada, Evraz Inc. NA) the project will train four Ph.D. students and two postdoctoral fellows who will gain expertise in atomic scale resolution characterization and state-of-the-art computational techniques. Engineers with this expertise will be essential for Canada's metal producers and users to remain globally competitive.**********