Role of Minor Alloying Elements in the Corrosion of Selected Amorphous Alloys

技术概述：在金属合金中获得优异耐腐蚀性的传统方法包括添加金属和类金属元素，其浓度达到形成钝化膜、抑制坑内活性溶解或达到分离极限所需的浓度。与脱合金化有关。结构和化学缺陷也受到非均质材料中受控合金化添加的影响。非晶态金属包含了许多这样的策略：结构和化学异质性被最小化，亚稳态过饱和固溶体通常与大量有益的合金元素一起形成。然而，很少有人研究微量合金化添加剂对耐蚀性可能起到的有益作用(S)。然而，少量的合金元素提供了大量机会来提高许多金属材料的耐腐蚀性。事实上，在过去的100年里，这一策略在合金耐腐蚀性方面取得了一些最大的进步。这项工作将通过系统的添加和纳米和微米尺度的表征和模拟来研究微量有益合金化在两个固溶体系统中的作用：含有少量B，Y，W和Si的非晶态Fe-Cr-Mo-C合金以及含有少量Ni或Pd的Al-Cu-Mg合金。存在几个可测试的假设；其中一些将在拟议的工作中进行探索。少量合金元素会影响结合和/或在合金中形成原子团簇，而合金元素不那么贵重，容易腐蚀，从而改变它们本来优先氧化的倾向。较高的熔化温度、贵重的微量合金元素缺乏表面流动性，这些相对不活跃的物种会阻碍溶解金属表面的溶解位置。微量合金元素还可以改变氧化物或合金中的溶质扩散速率，从而作为有利于耐腐蚀性的合金元素比率的试剂运行。非技术摘要：工程材料的腐蚀是一个威胁安全、健康、安保、清洁水需求和能源独立的国际重要问题。在美国，每年的成本超过3000亿美元。新培训的腐蚀科学家和工程师也日益短缺，这与全国工程学毕业生短缺有关。该项目不仅支持开发用于安全和能源应用的增强型合金所必需的基本理解，而且还支持腐蚀科学领域的人力资源开发？这是美国国家科学院确定的一个关键需求。该项目将为2名材料科学与工程专业的研究生提供基于多学科知识的教育，从而为腐蚀冶金领域提供所需的专业人才。弗吉尼亚大学电化学科学与工程中心培训腐蚀和材料科学/工程等多学科领域的学生，是向美国工业界、政府和学术界提供具有此类知识的专业人员的主要供应商。代表不足的性别和族裔学生是这一综合培训和研究努力的优先和持续重点。学生通过广泛感兴趣的论文和书籍、专业论文、会议、短期课程和K-12学生的实验室参观/演示来传播科学成果。

TECHNICAL SUMMARY:Traditional methods to obtain excellent corrosion resistance in metallic alloys include addition of metallic and metalloid elements up to the concentrations necessary to either form passivating films, inhibit active dissolution in pits, or reach the ?parting limit? associated with dealloying. Structural and chemical defects have also been affected by controlled alloying additions in heterogeneous materials. Amorphous metals incorporate many of these strategies: structural and chemical heterogeneities are minimized, and metastable supersaturated solid solutions are often formed with large concentrations of beneficial alloying elements. However, the possible beneficial role(s) of minor alloying additions on corrosion resistance are rarely explored. Yet, minor alloying elements offer substantial opportunities to improve the corrosion resistance of many metallic materials. Indeed, this strategy has provided some of the greatest gains in alloy corrosion resistance in the last 100 years. This work will investigate the role of trace beneficial alloying additions in two solid solution systems: amorphous Fe-Cr-Mo-C alloys containing small concentrations of B, Y, W and Si as well as in Al-Cu-Mg alloys containing small amounts of Ni or Pd through systematic additions and nano- as well as micro-meter scale characterization and modeling. Several testable hypotheses exist; some of these will be explored in the proposed work. Minor alloying elements can affect bonding and/or form atomic clusters in the alloy with less noble, corrosion prone alloying elements to alter their otherwise preferential oxidation tendency. High melting temperature, noble minor alloying elements lack surface mobility and these relatively immobile species could block dissolution sites on the surface of dissolving metals. Minor alloying elements could also alter the solute diffusion rates in the oxide or alloy, thus operating as agents that shift alloying element ratios favorably for corrosion resistance.NON-TECHNICAL SUMMARY:Corrosion of engineering materials is an issue of international importance that threatens safety, health, security, needs for clean water and energy independence. The annual cost in the US exceeds 300 billion dollars per year. There is also a growing shortage of newly trained corrosion scientists and engineers connected with the national shortage of engineering graduates. This project not only supports the fundamental understanding necessary for development of enhanced alloys for security and energy applications but also supports human resource development in the area of corrosion science ? a crucial need identified by the National Academy of Sciences. This project provides the venue for the multi-disciplinary knowledge-based education of 2 graduate students in Materials Science and Engineering that will then provide needed professionals in the corrosion-metallurgy field. The Center for Electrochemical Science and Engineering at the University of Virginia trains students in the multi-disciplinary areas of corrosion and materials science/engineering and is a major supplier of professionals with such knowledge to US industry, government, and academia. Under-represented gender and ethnic students are a proven prior and on-going emphasis of this integrated training and research endeavor. Students disseminate scientific results in broad interest papers and books, specialty papers, conferences, short courses and lab tours/demos for K-12 students.