CAREER: Effects of Alloy Concentration on the Tribocorrosion Resistance of Al-TM Supersaturated Solid Solutions

非技术描述：摩擦腐蚀是由磨损和腐蚀共同作用引起的材料退化过程。这是最近兴起的一个研究领域，受生物医学植入物、核能发电、海洋和海洋工业等对耐磨和耐腐蚀材料的需求增加的推动。摩擦腐蚀的复杂性在于化学和机械攻击协同作用导致加速失效。这种协同效应对于不锈钢、钛和铝合金等钝化金属最为显著，它们依靠一层薄薄的表面氧化膜(钝化膜)作为防腐屏障。当腐蚀过程中发生机械磨损时，钝化膜可能会被局部破坏，随之而来的钝化会导致快速腐蚀和早期部件失效。本研究旨在通过实验和模拟来深入了解钝化金属在摩擦腐蚀过程中的退化机理。研究结果可为新型耐磨合金和涂层的开发提供参考。为本科生和代表不足的少数族裔创造了研究机会和导师计划。更新了相关的本科核心课程，纳入了与摩擦腐蚀有关的主题。该推广计划的特色是为佛罗里达州皮内拉斯县的小学和中学的女孩提供动手示范，以激发她们对STEM领域的兴趣。在流行的社交媒体平台上发布和推广演示与这项研究相关的物理概念的视频，以教育广大和不同的受众关于摩擦腐蚀的知识。技术细节：铝具有优异的耐腐蚀性，但耐划性较差，这极大地限制了其在机械接触和腐蚀性环境共存的工业应用中的潜在用途。本课题组最近的研究表明，在过饱和固溶体中将过渡金属(TM)与Al合金化，有可能同时提高铝合金的耐磨性和钝化层的保护性，从而提高整体的耐摩擦腐蚀性能。本研究项目旨在确定合金浓度如何影响摩擦腐蚀过程中的变形和退化，并集中于一项综合研究，包括材料加工、表征、摩擦腐蚀测试和理论建模。建议的加工技术可生产不同合金浓度的材料，同时将晶体织构和残余应力影响降至最低。对材料进行特定部位的表征，以评估摩擦腐蚀过程中不同的降解机制，包括磨损和腐蚀以及它们之间的协同和随机方面所引起的微观结构修改。具体的技术目标包括(1)建立Al-TMS的合金浓度/耐磨性关系，(2)确定是否存在最佳耐磨性的合金浓度，以及(3)研究服役条件(例如，施加的载荷、滑动速度)和腐蚀条件是否(以及如何)影响耐磨性。所获得的结果有助于为金属在恶劣环境和使用条件下的应用建立更好的指导方针。这些发现还有助于改进新型耐磨铝合金的设计原则，这种合金的使用为提高全球能源消耗的可持续性提供了巨大的潜力。

NON-TECHNICAL DESCRIPTION: Tribocorrosion is a material degradation process caused by the combined effects of wear and corrosion. It is a research area that emerged recently, driven by increased demand for wear- and corrosion-resistant materials from biomedical implants, nuclear power generation, marine and offshore industries, etc. The complexity of tribocorrosion lies in the fact that the chemical and mechanical attacks act synergistically to cause accelerated failure. The synergetic effect is most prominent for passive metals, such as stainless steels, titanium and aluminum alloys, which rely on the presence of a thin surface oxide film (passive film) as a protective barrier against corrosion. When mechanical wear takes place during corrosion, the passive film can be locally destroyed, with the ensuing depassivation leading to rapid corrosion and early component failure. This research seeks to offer insight concerning the degradation mechanisms during tribocorrosion of passive metals using experiments and modeling. The obtained results can lead to the development of new tribocorrosion resistant alloys and coatings with enhanced durability. Research opportunities and a mentorship program are created for undergraduate students and under-represented minorities. Relevant core undergraduate courses are updated to include tribocorrosion-related topics. The outreach program features hands-on demonstrations for girls in elementary and middle schools from Pinellas County, Florida, to stimulate their interest in STEM fields. Published and promoted videos demonstrating the physical concepts related to this research are on popular social media platforms to educate a broad and diverse audience about tribocorrosion. TECHNICAL DETAILS: Al exhibits excellent corrosion resistance but poor scratch resistance, which greatly limits its potential usage in industrial applications where mechanical contact and corrosive environment coexist. Recent studies from our group demonstrates that alloying Al with a transition metal (TM) in supersaturated solid solution has the potential of simultaneously increasing the wear resistance of Al alloys as well as the protectiveness of the passive layer, thus improving the overall tribocorrosion resistance. This research project is directed towards identifying how alloy concentration affects deformation and degradation during tribocorrosion and is centered on a comprehensive study that integrates material processing, characterization, tribocorrosion testing, and theoretical modeling. The proposed processing technique produces materials with various alloy concentrations while minimizing crystallographic texture and residual stress effects. Materials are characterized site-specifically to evaluate the microstructural modifications induced by different degradation mechanisms during tribocorrosion, including wear and corrosion and their synergistic and stochastic aspects. The specific technical objectives include (1) establishment of the alloy concentration/tribocorrosion resistance relationship for Al-TMs, (2) determination of whether an optimum alloy concentration exists for the best tribocorrosion resistance, and (3) investigation of whether (and how) in-service conditions (e.g., applied load, sliding speed) and corrosion conditions influence the tribocorrosion resistance. The obtained results help establish better guidelines for the application of metals in harsh environments and service conditions. The findings also serve to improve design principles for new tribocorrosion-resistant Al alloys, the use of which presents great potential for increasing the sustainability of global energy consumption.