EAGER: Stability and Nanocrystallization Kinetics of Amorphous Al Alloys

EAGER：非晶铝合金的稳定性和纳米结晶动力学

• 批准号: 1005334
• 负责人: John Perepezko
• 金额: $ 18.51万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-01 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005334&HistoricalAwards=false
• 关键词: EAGER; Stability; Nanocrystallization; Kinetics; Amorphous

TECHNICAL SUMMARY: An important form of bulk nanostructured alloys is based upon a high density dispersion of nanocrystals in an amorphous matrix. Crystallization from an amorphous matrix is a preferred synthesis method in order to allow the control and tailoring of the microstructure and therefore properties such as high strength. Since the strength depends on the particle size and volume fraction, understanding and controlling the mechanisms of primary aluminum nanocrystal formation with number densities of 1021 ? 1023 m-3 dispersed in an amorphous matrix are of special interest. While the technological significance of this microstructure design is clear, the fundamental understanding of the controlling nucleation and growth kinetics has not been resolved for the early stage evolution of nanocrystals. Moreover, recent nanoscale structural analysis has revealed that the atomic arrangements in the amorphous phase are spatially heterogeneous so that a new model that will be advanced in this study is required to account for the kinetic effects of spatial heterogeneities. In order to provide the database to test the fidelity of the unproven kinetics analysis, nanocrystal nucleation and structural characterization will be studied systematically in Al-Y-Fe amorphous alloys with minor alloying. An important outcome from a successful project will be the formulation of a new paradigm for the kinetics analysis of nanoscale microstructure synthesis in heterogeneous materials.NON-TECHNICAL SUMMARY: The nanoscale microstructures that evolve during primary crystallization of amorphous alloys in bulk volumes are responsible for the attractive structural and functional materials properties that have technological applications in transportation and communications. In order to develop nanoscale microstructures it is essential to understand the controlling reaction kinetics so that the nanocrystal number density is maximized and the growth is limited. Previous kinetics models have treated the amorphous phase as uniform on an atomic scale, but recent structural analysis has revealed atomic scale spatial heterogeneities. A new kinetics analysis will be developed to treat the spatially heterogeneous state and tested with nanocrystal nucleation measurements in amorphous Al-Y-Fe alloys. The results have a broader relevance to the nature of primary crystallization as a common devitrification reaction in many metallic glasses. An important component of the project effort will be the education of graduate students and the research experience for undergraduate and high school students. Further, lecture demonstrations on nanostructured materials will be incorporated into campus outreach programs for high school and incoming undergraduate students.

技术摘要：散装纳米结构合金的一种重要形式是基于无定形基质中纳米晶体的高密度分散。从无定形基质中结晶是一种首选合成方法，以控制和定制微观结构，因此诸如高强度之类的特性。由于强度取决于粒径和体积分数，因此了解和控制原代铝纳米晶体形成的机制，数量密度为1021？分散在无定形基质中的1023 M-3是特别感兴趣的。尽管这种微观结构设计的技术意义很明显，但对控制成核和生长动力学的基本理解尚未解决纳米晶体的早期演变。此外，最近的纳米级结构分析表明，无定形阶段的原子布置在空间异质上是异质性的，因此需要在这项研究中采用的新模型以说明空间异质性的动力学效应。为了提供数据库来测试未经证实的动力学分析的忠诚度，将在具有较小合金的Al-Y-Y-FE无定形合金中系统地研究纳米晶体成核和结构表征。成功项目的一个重要结果将是为异构材料中的纳米级微观结构合成动力学分析的新范式的制定。Non-Technical摘要：纳米级微结构，这些微结构在体积和功能性材料中的无用材料中的无相合金中的初级结晶过程中的初级结晶过程中进化，并且具有有吸引力的结构材料和具有技术性的技术。为了开发纳米级微观结构，必须了解控制反应动力学，以便最大化纳米晶体数密度并有限。以前的动力学模型已将无定形相视为原子量表均匀的，但是最近的结构分析揭示了原子量表空间异质性。将开发一种新的动力学分析，以治疗空间异质状态并用无定形的Al-Y-FE合金中的纳米晶体成核测量进行了测试。结果与原代结晶的性质具有更广泛的相关性，这是许多金属玻璃中常见的脱发反应。项目工作的重要组成部分是研究生的教育以及本科生和高中生的研究经验。此外，关于纳米结构材料的演示将纳入高中和入学的本科生的校园外展计划中。