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

铝镁合金早期沉淀硬化现象的多尺度研究

• 批准号: RGPIN-2015-04555
• 负责人: Esmaeili, Shahrzad
• 金额: $ 1.82万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613033
• 关键词: Multi; length; scale; studies; early

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.

热处理AA6xxx（即Al-Mg-Si-(Cu)）合金是最广泛使用的结构材料之一，因为它们具有理想的性能组合。这些合金用于几类豪华汽车或卡车的面板应用。然而，轻量化的迫切性也引起了人们对其在主流汽车中的应用的极大兴趣。这些面板通常由冷冲压制成，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更低的温度。如果合金成分和/或加工历史没有适当优化，这些工艺要求可能会将沉淀限制在相对较早的阶段，并对硬化产生不利影响。这种优化和设计高强度合金和成本有效的加工路线需要对控制溶质聚集和早期沉淀现象的机制有深刻的理解。申请人在该领域的最新工作突出了在铝合金时效硬化过程中发生的早期现象的知识方面的主要差距。特别是，需要进行全面的原子到宏观长度尺度的研究，以了解合金成分、变形和早期沉淀硬化动力学之间的关系。