Multi-length scale studies of early stage precipitation hardening phenomena in Al and Mg alloys

可热处理的AA 6xxx（即，Al-Mg-Si-（Cu）合金由于其所需性能的组合而属于最广泛使用的结构材料。 这些合金用于几类豪华汽车或卡车的面板应用。然而，轻量化的紧迫性也使人们对它们在主流汽车中的使用产生了极大的兴趣。这些面板通常通过冷冲压制造，然后在烤漆循环（PBC）期间沉淀硬化。优化PBC的工业趋势是缩短加热时间和使用较低的温度。如果合金成分和/或加工历史没有适当地优化，这些工艺要求可以将沉淀限制在相对早期的阶段，并且不利地影响硬化。 这种优化和设计更高强度的合金和成本有效的处理路线需要深刻理解的机制，支配溶质聚集和早期沉淀现象。申请人在该领域的最新工作突出了在Al合金的时效硬化期间发生的早期现象的知识的主要差距。特别是，需要进行全面的原子到宏观尺度的研究，以了解合金成分、变形和早期沉淀硬化动力学之间的关系。镁在工程金属中密度最低，在交通运输的结构应用中也具有重要意义。然而，目前可用的锻造合金的性能的缺点对其实际应用构成严重障碍。最近，申请人和他以前的学生设计了具有有希望的性能组合的非常有吸引力的Mg-Zn-Ca-Ce合金。然而，合金优化和这些合金的最终使用需要进一步研究其沉淀硬化行为的基本原理。建议的工作是建立在上述背景下，旨在研究的作用，合金化学，变形和热处理历史的早期阶段的沉淀和随后的硬化AA 6xxx合金，和Mg-Zn-Ca-（Ce）合金。多长度尺度实验和建模方法将用于分析上述合金类别中选定组的加工-结构-性能关系的基本原理。* 这项研究将创造重要的新知识，并为设计新的高强度轻合金和部件以及具有成本效益的工艺铺平道路。这一结果对加拿大的制造业和汽车行业非常重要。它还将导致培训能够很好地为加拿大的教育和工业机构服务的高素质人才。************ **

Heat treatable AA6xxx (i.e., Al-Mg-Si-(Cu)) alloys are among the most widely used structural materials owing to their combination of desirable properties. These alloys are used for panel applications in several classes of luxury automobiles or trucks. However, the urgency for lightweighting has created significant interest in their use in main stream automobiles, as well. These panels are commonly-fabricated by cold stamping and then precipitation hardened during paint bake cycling (PBC). The industrial trend in optimizing PBC is towards shortening heating times and using lower temperatures. These process requirements can limit precipitation to relatively early stages and adversely affect hardening, if alloy compositions, and/or processing histories are not properly optimized. Such optimizations and the design of higher strength alloys and cost effective processing routes requires a deep understanding of the mechanisms that govern solute clustering and early stage precipitation phenomena. The applicant's most recent work in this area has highlighted the major gaps in knowledge of the early-stage phenomena that occur during age hardening of Al alloys. Particularly, a comprehensive atomic-to-macro length scale investigation is needed to understand the relationships between alloy compositions, deformation and the kinetics of early-stage precipitation hardening.***Magnesium, with its lowest density among engineering metals, is of significant interest for structural applications in transportation, as well. However, the shortcomings in the properties of currently-available wrought alloys pose serious obstacles to their practical use. Recently, the applicant and his former student have designed highly attractive Mg-Zn-Ca-Ce alloys with promising combination of properties. However, alloy optimization and the eventual use of these alloys require further investigations into the fundamentals of their precipitation hardening behaviour.***The proposed work is built on the above background and aims to investigate the role of alloy chemistry, deformation and thermal processing histories on the early stage precipitation and subsequent hardening in AA6xxx alloys, and Mg-Zn-Ca-(Ce) alloys. Multi-length scale experimental and modeling approaches will be used to analyze the fundamentals of processing-structure-property relationships in selected sets of the above alloy classes. ***This investigation will create significant new knowledge and pave the way for designing new high strength light alloys and components, as well as cost-effective processes. Such outcome will be highly important for Canada's manufacturing and automotive sectors. It will also lead to the training of highly-qualified personnel which can well serve Canada's educational and industrial institutions. ************ **