Sculpting Energy Landscapes in Materials: Theory, Experiment and Application

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An essential feature of humanity's development has been its mastery of materials, from blacksmiths pounding metal into weapons to robots depositing atoms layer-by-layer for the electronic gadgets revolutionizing our communications. Today, constrained by finite mineral resources and environmental necessity, our future demands even greater mastery, in effect more from less. We are already facing these challenges - extending the lives of power plants, building safer and lighter vehicles, and searching for higher energy density solutions in batteries. At the heart of the problem to make materials perform better is to understand and control its internal structure. A materials structure spans the sub-nanometer to millimeter length scales with space filled in-between by phases interconnected by boundaries that together is the microstructure. Materials scientists and engineers have known for a long time the importance of grain boundaries on engineering properties. Special boundaries have been observed in some materials that self-heal when damaged, which could prevent failures in structural materials. The grain boundaries role in materials performance is analogous to the multiple-door hallway set-up in film comedies, where many actors enter, hang-out, or quickly leave, depending upon whether they need to meet someone, or escape from something. Unlike hallways though, we are far away from being able to identify and master even a fraction of the grain boundary scenarios possible in real materials, because these structures are difficult to observe, describe, and control.Materials are useful when the structures that control properties do not change. However, materials are never truly at equilibrium and are instead “lulled” into metastable states consisting of a distribution of chemical and structural features that together constitute an energy landscape. In the simplest sense this landscape self-organizes when we do work on it, i.e. drawing piano wire re-orients internal crystals, dissolves phases and patterns internal defects. Grain boundaries change too, as energy ebbs and flows through its hallway/door structure.This research will for the first time study how metals containing boundaries dissipate energy when they are pushed into highly energized states using a new high-energy beam source at Queen's. Four graduate students will study how the beam sculpts the energy landscape of the microstructure creating new and distinctive features that will help better understand the grain boundary structure. The work will support materials applications in Canada's technology sectors operating in extreme environments such as nuclear reactors, outer space systems, and Canada's future high-speed train.