Quantification of 3-D Effects of Microstructure on Fatigue Crack Initiation and Early Growth in Planar Slip Alloys

微观结构对平面滑移合金疲劳裂纹萌生和早期扩展的 3D 影响的量化

• 批准号: 1207115
• 负责人: Tongguang Zhai
• 金额: $ 27.14万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207115&HistoricalAwards=false
• 关键词: Quantification; Effects; Microstructure; Fatigue; Crack

TECHNICAL SUMMARY:The PI of this research project proposes to develop a microstructure-based model to quantify fatigue crack initiation and early growth in a planar slip alloy, such as AA2026, 2524, and 2099 Al alloys, first, by identifying the quantitative relationship between short fatigue crack resistance and the twist component of crack plane deflection across either the particle-matrix interface or grain boundaries and, second, by calculating the growth rate of a micro-crack initiating from a particle and taking into account both the driving force and resistance in three dimensions in these alloys. A focused ion beam will be employed to fabricate a micro-notch having a controlled twist angle with the primary slip plane in a coarse grain of the alloy and to make serial cross-sections of fractured particles found in the sample surface after fatigue. The resistance to micro-crack growth from the notch will be extracted from measured crack growth rate data as a function of the twist angle. Incorporation of both the resistance and driving force in the PI's crystallographic model will enable quantification in three dimensions of the growth behavior of the micro-crack from a particle in the surface of the alloys. Using this model will allow identification of the desirable microstructure and texture for optimum high-cycle fatigue properties in the alloys. The model will also help to elucidate the mechanism for the observed differences in micro-crack growth behavior among different particles on a surface in the alloys.NON-TECHNICAL SUMMARY:This project is expected to result in improved fatigue properties in aluminum alloys, which may have significant impact on the aerospace and automotive industries. In this regard, the proposed research has potential for wider societal impacts. The alloy industry as a whole will also benefit from the methodology to be developed, as identification of the desirable microstructure and texture that lead to optimum fatigue resistance in high-performance alloys will advance alloy design. Further, this research project will help to develop well-trained young technical graduates for the aluminum, automotive, and aerospace industries. The PI will integrate the research work into his teaching activities by developing two projects, related to project findings, for use in his materials science and engineering courses. Undergraduate students will also participate by creating three-dimensional animation models of crack growth across grain boundaries, three-dimensional microstructure, and X-ray diffraction. These models will be made available on a website, together with the latest research results, for access by the public. The PI will also organize a symposium series on fatigue damage in metallic materials at The Mineral, Metals & Materials Society annual meetings to disseminate effectively research findings among members of the research community and engineers from the alloy industry.

技术摘要：该研究项目的主要负责人建议开发一种基于微观结构的模型，以量化平面滑移合金（例如 AA2026、2524 和 2099 铝合金）中的疲劳裂纹萌生和早期生长，首先，通过确定短疲劳裂纹抗力与跨越颗粒基体界面或晶界的裂纹平面偏转的扭转分量之间的定量关系，其次，通过计算生长速率 分析从颗粒开始的微裂纹，并考虑这些合金的三维驱动力和阻力。将采用聚焦离子束在合金粗晶粒中制造与主滑移面具有受控扭转角的微凹口，并制作疲劳后在样品表面中发现的断裂颗粒的连续横截面。将从测量的裂纹扩展速率数据中提取对凹口微裂纹扩展的抵抗力，作为扭转角的函数。将电阻和驱动力纳入 PI 的晶体学模型中，将能够在三个维度上量化合金表面颗粒的微裂纹的生长行为。使用该模型将能够识别理想的微观结构和织构，以实现合金的最佳高周疲劳性能。该模型还将有助于阐明观察到的合金表面不同颗粒之间微裂纹扩展行为差异的机制。非技术摘要：该项目预计将改善铝合金的疲劳性能，这可能对航空航天和汽车工业产生重大影响。在这方面，拟议的研究有可能产生更广泛的社会影响。 整个合金行业也将从待开发的方法中受益，因为确定理想的微观结构和织构以提高高性能合金的最佳抗疲劳性将推进合金设计。此外，该研究项目将有助于为铝、汽车和航空航天行业培养训练有素的年轻技术毕业生。 PI 将通过开发两个与项目成果相关的项目，将研究工作融入到他的教学活动中，用于他的材料科学和工程课程。本科生还将参与创建跨越晶界的裂纹扩展、三维微观结构和 X 射线衍射的三维动画模型。这些模型将与最新的研究结果一起发布在网站上，供公众访问。 PI 还将在矿物、金属和材料协会年会上组织金属材料疲劳损伤系列研讨会，以便在研究界成员和合金行业工程师中有效传播研究成果。