CAREER: Understanding the Corrosion Fatigue Behavior of Additively Processed Metals through an Integrated Experimental and Computational Approach

该学院早期职业发展（Career）奖将侧重于确定控制增材制造金属腐蚀疲劳行为的机制，特别是由于独特的微观结构特征和加工过程中引入的残余应力的影响。增材制造近年来受到广泛关注，因为它可以用于生产几何和成分复杂的零件，以及提供按需生产和维修能力。然而，由于几个问题，它制造真正承重部件的潜力尚未完全实现。特别是，由此产生的显微组织特征的复杂性使得很难区分它们各自对断裂和疲劳性能的影响。该项目将回答两个相关的问题，重点是腐蚀环境：1)在正常和腐蚀环境下，增材加工合金的疲劳行为与传统合金有何不同？2)微观结构如何导致观察到的行为差异？从该奖项中获得的见解将指导增材制造零件的设计和制造，并通过限制腐蚀环境中疲劳失效的原因来延长其使用寿命。因此，这项研究不仅将促进科学的进步，而且将通过减少与腐蚀损害相关的巨大经济损失来促进国家的繁荣和福祉。此外，该奖项将通过发起“飞行中的女性”俱乐部，并通过创造性的视听学习模块向高中科学教师和学生进行推广，以鼓励工程领域的女性。增材制造金属中形成的独特微观结构值得深入研究其对环境辅助疲劳行为的影响。该项目将采用计算和实验相结合的方法：1)通过高周疲劳试验评估传统和增材制造合金在空气和腐蚀环境中的宏观疲劳性能；2)利用电化学微电池和自适应动力学蒙特卡罗建模技术阐明微观特征和缺陷对局部钝化和腐蚀性能的影响；3)通过开发基于相场和晶体塑性建模的微结构敏感多物理场计算框架，揭示微观结构特征和缺陷及其相互作用的机理和影响。将考虑的特征是亚晶位错网络，凝固织构，孔隙率，化学非均质性，以及残余应力。通过实验验证的模型框架有望为进一步了解增材制造合金在腐蚀环境中的变形和破坏机制提供新的能力。该奖项反映了美国国家科学基金会的法定使命，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。

This Faculty Early Career Development (CAREER) award will focus on determining the mechanisms governing the corrosion fatigue behavior of additively manufactured metals, especially due to the influence of unique microstructural features and residual stress introduced during processing. Additive manufacturing has gained wide attention in recent years because it can be used to produce geometrically and compositionally complex parts, as well as provide on-demand production and repair capability. Its potential to manufacture true load-bearing parts, however, is not yet fully realized due to several issues. In particular, the complexity of the resultant microstructural features makes it difficult to distinguish their respective effects on fracture and fatigue performance. This project will answer two relevant question with focus on corrosive environments: 1) How does the fatigue behavior of additively processed alloys differ from that of their conventional counterparts under normal and corrosive environments, respectively? and 2) How does the microstructure contribute to the observed differences in behavior? Insights gained from the award will guide the design and manufacture of additively manufactured parts and prolong their service life by limiting the causes of fatigue failure in corrosive environments. Thus, the research will not only promote the progress of science but will also advance national prosperity and welfare by reducing the tremendous financial losses related to corrosion damage. In addition, this award will encourage women in engineering by launching a “Women in Flight” club and perform outreach to high school science teachers and students through creative audiovisual learning modules.The unique microstructure formed in additively manufactured metals merit critical investigation into its effect on environmentally-assisted fatigue behavior. This project will employ a combined computational and experimental approach to: 1) evaluate the macroscopic fatigue properties of conventional and additively manufactured alloys in air and corrosive environment using high-cycle fatigue testing; 2) elucidate effects of microscopic features and defects on the local passivity and corrosion properties using electrochemical microcell and adaptive Kinetic Monte Carlo modeling techniques, and 3) reveal the mechanism and the influence of individual microstructure features and their interaction by developing a microstructure-sensitive multiphysics computational framework based on phase field and crystal plasticity modeling. The features that will be considered are sub-grain dislocation networks, solidification texture, porosity, and chemical heterogeneity, as well as residual stress. It is expected that he experimentally-validated modeling framework will introduce a new capability to advance the mechanistic understanding of deformation and failure of additively manufactured alloys in corrosive environment.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.