Sculpting Energy Landscapes in Materials: Theory, Experiment and Application

人类发展的一个基本特征是对材料的掌握，从铁匠将金属锻造成武器，到机器人为彻底改变我们通讯方式的电子设备逐层沉积原子。今天，受有限的矿产资源和环境需求的限制，我们的未来需要更大的掌握，实际上是事半功倍。我们已经面临着这些挑战——延长发电厂的寿命，建造更安全、更轻的车辆，以及寻找更高能量密度的电池解决方案。使材料性能更好的核心问题是了解和控制其内部结构。材料结构跨越亚纳米到毫米的长度尺度，中间的空间由由边界连接在一起的相填充，这就是微观结构。材料科学家和工程师很早就知道晶界对工程性能的重要性。在一些材料中观察到特殊的边界，当损坏时自愈，这可以防止结构材料的失效。材料性能中的晶界作用类似于电影喜剧中的多门走廊设置，许多演员进入，闲逛或迅速离开，这取决于他们是否需要遇见某人或逃离某事。然而，与走廊不同的是，我们还远远不能识别和掌握真实材料中可能出现的晶界场景的一小部分，因为这些结构很难观察、描述和控制。当控制性质的结构不变时，材料是有用的。然而，物质从来没有真正处于平衡状态，而是被“哄骗”进入亚稳态，亚稳态由化学和结构特征的分布组成，这些特征共同构成了一个能量景观。从最简单的意义上说，当我们在这个景观上工作时，它会自我组织，例如，绘制钢琴线，重新定位内部晶体，溶解相和图案内部缺陷。当能量在走廊/门结构中涨落时，晶界也会发生变化。这项研究将首次研究含有边界的金属在皇后大学使用一种新的高能光束源将其推入高能量状态时是如何耗散能量的。四名研究生将研究光束如何塑造微观结构的能量景观，创造新的和独特的特征，这将有助于更好地理解晶界结构。这项工作将支持加拿大技术部门在极端环境下的材料应用，如核反应堆、外层空间系统和加拿大未来的高速列车。

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.