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CAREER: Understanding the Role of Cu-Containing Secondary Phase Particles in Enhancing the Resistance to the Environmental Acceleration to Fatigue in Age-Hardenable Al Alloys

事业：了解含铜第二相颗粒在增强时效硬化铝合金的环境加速疲劳抵抗力方面的作用

基本信息

批准号：
1943870
负责人：
Jenifer Locke
金额：
$ 53.15万
依托单位：
Ohio State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-01 至 2025-05-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1943870&HistoricalAwards=false
关键词：
CAREER Understanding Role Cu Containing

项目摘要

Non-Technical Summary: In order to address the existential crisis of global climate change and our aging infrastructure, dramatically improving the sustainable use of metals utilized in our infrastructure (examples include aluminum used for aircraft, automobiles, and bridges and steels used for ships, automobiles, bridges, and nuclear waste storage) is required. A major problem when considering the sustainable use of metals is environmental degradation through corrosion processes and the need for engineers educated in both environmental degradation (specifically corrosion and related cracking) and materials science. In everyday life, corrosion is most easily seen as rust; but in aging infrastructure it can go unseen and cause catastrophic failures that severely limit sustainable long-term use of engineered metal structures. This research pushes to understand why some aluminum based metals have inherently better resistance to the environmental acceleration of cracking and associated failures than others. Knowledge that could be utilized to improve the performance and the long term sustainable use of metals that have lower environmental resistance to cracking. Through these research endeavors, a graduate student and 5 years of REU (Research Experience of Undergraduates) and RET (Research Experience for Teachers) participants are being introduced to and trained in corrosion and materials science. Additionally, a wide range of students and future engineers are being exposed to materials science and corrosion as the research team develops corrosion related demos and social media videos. Finally, this research is establishing bonds between the PI’s research lab at The Ohio State University, a local Columbus K-12 school, and an education focused university in Ohio, Wittenberg University, which will go far beyond the short-term goals. Technical Summary: Corrosion and environment assisted cracking (EAC) play critical roles in sustainability. Research and education in corrosion and EAC is critical to ensuring our society addresses the sustainable use of metals to save energy and reduce consumption. Research has established that some age-hardenable aluminum alloys have better resistance to EAC than others, but an underlying mechanism for this has yet to be confirmed. Specifically, Al-Cu based Al alloys are inherently more resistant to the environmental acceleration of fatigue crack growth than Al-Zn based Al alloys. This research tests the hypothesis that age-hardenable Al alloys with metallurgical secondary phases that promote Cu re-depostion during corrosion (Al-Cu based Al alloys) have an intrinsic resistance to the environmental acceleration to fatigue crack growth as a result of crack wake surface Cu enrichment catalyzing cathodic reaction(s) within the crack environment. This self-mitigates the adverse acidic environment established to drive EAC in 7xxx age-hardenable Al alloys, which are of higher susceptibility. The less acidic crack solution pH reduces environmental sensitivity and corrosion fatigue susceptibility by reducing crack tip H uptake through the stabilization of a crack tip passive film. The following approaches are being used to test this hypothesis. First, fracture mechanics approaches are being utilized to probe corrosion fatigue sensitivity of Al alloys with specific Zn, Mg, and Cu concentrations as a function of fatigue loading frequency and load waveform. In addition, near crack tip pH is being directly probed utilizing mini-flexible pH electrodes inserted into the fracture mechanics samples. Finally, crack tip pH is being altered to either promote or mitigate corrosion fatigue as a final confirmation. This research is being performed by a team that includes the principal investigator, a sponsored graduate student, and RET and REU participants with the goal of training and engaging a diverse team throughout the research program. Together this research team is also collaboratively developing corrosion related materials science demos that will be deployed at the REU’s and RET’s home institutions and in the Introduction to Materials Science course at The Ohio State University. Social media videos are also being created to showcase the developed demos and the diverse research team with the mission of educating on the science of corrosion and how it impacts sustainability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术总结：为了应对全球气候变化和基础设施老化的生存危机，需要大幅提高基础设施中使用的金属的可持续利用（例如用于飞机，汽车和桥梁的铝以及用于船舶，汽车，桥梁和核废料储存的钢材）。在考虑金属的可持续使用时，一个主要问题是通过腐蚀过程造成的环境退化，以及需要在环境退化（特别是腐蚀和相关开裂）和材料科学方面受过教育的工程师。在日常生活中，腐蚀最容易被视为生锈;但在老化的基础设施中，它可能看不见并导致灾难性的故障，严重限制了工程金属结构的可持续长期使用。这项研究推动了解为什么一些铝基金属具有比其他金属更好的抗环境加速开裂和相关故障的能力。可用于改善性能和长期可持续使用的金属的知识，这些金属具有较低的环境抗裂性。通过这些研究工作，一名研究生和5年的REU（本科生研究经验）和RET（教师研究经验）参与者正在接受腐蚀和材料科学的培训。此外，随着研究团队开发与腐蚀相关的演示和社交媒体视频，各种学生和未来的工程师正在接触材料科学和腐蚀。最后，这项研究正在建立PI在俄亥俄州州立大学的研究实验室，当地哥伦布K-12学校和俄亥俄州的教育重点大学维滕贝格大学之间的联系，这将远远超出短期目标。技术总结：腐蚀和环境辅助开裂（EAC）在可持续性方面发挥着关键作用。腐蚀和EAC的研究和教育对于确保我们的社会解决金属的可持续使用以节省能源和减少消耗至关重要。研究已经确定，一些可时效硬化的铝合金比其他合金具有更好的耐EAC性，但其潜在机制尚未得到证实。具体地，Al-Cu基Al合金比Al-Zn基Al合金固有地更能抵抗疲劳裂纹生长的环境加速。本研究测试的假设，时效硬化的铝合金与冶金第二相，促进铜再沉积在腐蚀过程中（铝铜基铝合金）有一个固有的电阻环境加速疲劳裂纹扩展的结果，裂纹尾流表面铜富集催化阴极反应（S）在裂纹环境。这自缓解了为在7 xxx可时效硬化铝合金中驱动EAC而建立的不利酸性环境，7 xxx可时效硬化铝合金具有较高的敏感性。酸性较低的裂纹溶液pH通过裂纹尖端钝化膜的稳定化降低裂纹尖端H吸收来降低环境敏感性和腐蚀疲劳敏感性。以下方法可用于检验这一假设。首先，断裂力学方法被用来探测腐蚀疲劳敏感性的铝合金与特定的锌，镁，铜浓度作为疲劳载荷频率和载荷波形的函数。此外，裂纹尖端附近的pH值是直接探测利用微型柔性pH电极插入到断裂力学样品。最后，裂纹尖端pH值正在改变，以促进或减轻腐蚀疲劳作为最终确认。这项研究是由一个团队，其中包括主要研究者，赞助的研究生，RET和REU参与者与培训和参与整个研究计划的多元化团队的目标进行。该研究团队还共同合作开发腐蚀相关材料科学演示，这些演示将部署在REU和RET的家庭机构以及俄亥俄州州立大学的材料科学入门课程中。社会媒体视频也正在创建，以展示开发的演示和多样化的研究团队，其使命是教育腐蚀科学及其如何影响可持续性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。