Deformation Response of Oriented Crystalline Aggregates: Experiment and Theory

这项工作探讨了如何在定向结晶材料的微观结构介导的原子物理的强度和延展性的更大的宏观响应的滑移。 强度和延展性是现代社会使用的大多数结构材料的加工和服务中的基本特性，因此必须了解和控制它们。 在材料加工过程中，聚集体中晶粒的取向自然发展，某些理想取向变得比其他取向更常见。 通常这些理想的方向被不同水平的方向噪声所包围，这些噪声是尚未得到很好研究的弱次要或随机分量。 运输、包装和能源领域结构材料的主要供应商通常通过其专利工艺周期生产具有定制理想取向的材料，以利用所需的材料特性。 目前，多尺度模型可以预测加工过程中的平均取向发展，但无法捕获在加工过程中发展为“微观结构”的结晶物质中观察到的统计偏差。 这些变化可以归因于对变形的原子过程的理解的局限性，点缺陷如合金元素对集体变形行为的作用，以及内部界面或晶界对相邻晶体之间的滑移活动的影响。 作为一个前进的方向，这项工作的目标是（i）探索新的方法来制造理想取向的多晶材料，以研究（ii）试样尺寸和时间尺度对热激活变形过程的影响，（iii）变形或加热下取向和微观结构稳定性之间的联系，（iv）溶质原子杂质对不同铝合金体系中纳米孔洞稳定性的作用及其对整体塑性的影响。 这些研究确定了不同材料中的关键长度尺度特征，从这些特征中，现有和未来的加拿大金属供应商和制造商可以在新的功能材料中利用集体宏观现象，如超强度或表面粗糙化。

This work explores how the microstructure in oriented crystalline materials mediates the atomistic physics of slip to the larger macroscopic responses of strength and ductility. Strength and ductility are essential properties in the processing and service of most structural materials used by modern society, and so they are essential to understand and control. The orientations of crystalline grains in aggregates develop naturally during materials processing, with certain ideal orientations becoming more common than others. Often these ideal orientations are surrounded by different levels of orientation noise, which are weak minor or random components that have not been well studied. The primary suppliers of structural materials for transportation, packaging, and energy sectors usually produce materials with tailored ideal orientations obtained through their patented processing cycles to exploit desirable materials properties. Currently, multi-scale models can predict average orientation development during processing, but are unable to capture the statistical deviations observed in the crystalline matter developed as "microstructure" during processing. These variations can be attributed to limitations in understanding of the atomistic processes of deformation, the role of point defects such as alloying elements on collective deformation behaviour, and the effect of internal interfaces, or grain boundaries on communicating the slip activities between neighbouring crystals. As a way forward, the objective of this work is to (i) explore novel methods to fabricate ideally oriented polycrystalline materials so to investigate (ii) the effect of specimen size and time scales on the thermally activated process of deformation, (iii) the connection between orientation and microstructure stability under deformation or heating, and (iv) the role of solute atom impurities on the stability of nano-voids in different aluminum alloy systems and their effect on general plasticity. These studies identify key length scale features in different materials from which collective macroscopic phenomena such as ultra-strength or surface roughening might be exploited in new functional materials by existing and future Canadian metals suppliers and fabricators.