Simultaneous Synthesis and Consolidation of Amorphous Alloys

技术：非晶合金通常表现出不同寻常的、吸引人的物理和机械性能组合。它们的用途，特别是在结构应用中，由于难以批量生产而非常有限。该程序旨在解决形成大块非晶结构的固有问题。已知由某些二元合金体系的元素组成的多层薄膜结构在退火过程中由于系统中固有的热力学驱动力而非晶化。该项目将这种固态非晶合成与热等静压（HIP）巩固过程结合起来，而不是单独进行，这是迄今为止的常规做法。Ni和Ti元素粉末将采用机械合金化（MA）进行加工。铣削后的Ni-Ti合金粉末的片层结构模拟了合金元素的多层薄膜结构。为了有效的非晶化/固结，片层结构的间距将作为轧机能量输入和铣削时间的函数进行优化。为了进一步了解温度和压力对非晶化反应的协同影响，我们将在单轴热压机上对Ni和Ti两个薄板进行压制实验。这将使我们能够在简化条件下研究和模拟非晶化速率，但与HIP中的相似。我们将研究另一种二元合金体系，即Ni-Zr。该程序依赖于对热力学的基本理解和使用来创建大块非晶结构。这可能是违反直觉的，因为非晶合金加工科学通常通过严重依赖动力学考虑的策略进行。该方法与传统研究的不同之处在于，它试图将非晶合金的合成和巩固结合为一个步骤，而不是一个顺序的、系列的方法。该项目为研究热力学、合金理论、合金设计、加工科学、致密化科学、亚稳结构和材料表征的基础方面提供了一个极好的机会。非技术：该计划的成功将对解决技术困难产生重大影响，这些困难主要阻碍了非晶合金在批量结构应用中的实施。例如，它可以导致研究开发一种真正大块的铁基非晶合金，用作发电中电磁铁的核心；与传统的硅磁芯相比，这种磁芯已被证明提供约60%的高输出。来自弗吉尼亚理工大学的研究生和本科生，以及来自摩根州立大学的一名本科生将参加这个项目。该项目将寻求与摩根州立大学（MSU）的工程、物理和化学项目建立合作关系，摩根州立大学是马里兰州巴尔的摩的一所历史悠久的黑人学院和大学（HBCU）。尽管MSU以将大部分以上项目的毕业生送往国内顶级工程研究生院而闻名，但MSE作为一个非传统的工程项目很少被这些学生考虑。外展计划将在两所院校的教师和学生之间带来大量的教育和研究互动，从而向密歇根州立大学的学生介绍材料科学方面的职业选择和机会。预计这将导致其中一些学生在弗吉尼亚理工大学或其他工程机构注册MSE项目。该项目的研究结果也将有助于提高粉末加工课程的主题，该课程由PI教授给高年级本科生和研究生。

TECHNICAL: Amorphous alloys often exhibit unusual and attractive combinations of physical and mechanical properties. Their usefulness, especially in structural applications, has been very limited due to the difficulty in producing them in bulk form. This program seeks to address this inherent problem of forming bulk amorphous structures. Multilayer thin film structures comprised of the elements constituents of certain binary alloy systems are known to amorphize during annealing due to an inherent thermodynamic driving force in the system. The project combines this solid-state amorphous synthesis with a consolidation process by hot isostatic pressing (HIP) rather than doing either independently, which has been the normal practice to date. Elemental powders of Ni and Ti will be processed using mechanical alloying (MA). The lamella structure of the milled Ni-Ti alloy powder mimics the multilayer thin film structure of the elements of the alloy. Spacing in lamella structure will be optimized for effective amorphization/consolidation as a function of energy input from the mill and milling time. To further understand the cooperative influence of temperature and pressure on the amorphization reaction, an experiment will be developed in which two thin plates of Ni and Ti will be pressed in a uniaxial hot press. This will allow us to study and model the rate of amorphization under simplified conditions, but similar to those in the HIP. One other binary alloy system, namely Ni-Zr, will be studied. The program relies on the fundamental understanding and use of thermodynamics to create a bulk amorphous structure. This may be counter-intuitive, since amorphous alloy processing science generally proceeds via strategies that rely heavily on kinetic considerations. The approach differs from those in traditional studies in that it attempts to combine the synthesis and consolidation of amorphous alloys into a single step, rather than a sequential, series-type approach. The project represents an excellent opportunity to study fundamental aspects of thermodynamics, alloy theory, alloy design, processing science, densification science, metastable structures, and material characterization. NON-TECHNICAL: The success of this program will have a strong impact towards solving the technical difficulties that have mostly prevented the implementation of amorphous alloys in bulk, structural applications. It could, for example, lead to studies on the development of a truly bulk iron base amorphous alloy for use as the core for electromagnets in power generation; such a core has been shown to provide about 60% higher output as compared with the traditional silicon core. Graduate and undergraduate students from Virginia Tech, and one undergraduate student from Morgan State University, will participate in this program. This project will seek to develop a relationship with engineering, physics and chemistry programs at Morgan State University (MSU), one of the Historically Black Colleges and Universities (HBCU's) situated in Baltimore, MD. While MSU has a reputation for sending a large percentage of its graduates from the above programs to top engineering graduate schools in the country, MSE, being a non-traditional engineering program is rarely considered by these students. The outreach program will bring considerable educational and research interactions among faculty and students at both institutions, so as to introduce the students at MSU to career choices and opportunities in materials science. This is expected to lead to some of these students enrolling in MSE programs at Virginia Tech or other engineering institutions. The findings of project will also serve to enhance the subject matter of a powder processing course which the PI teaches to senior undergraduate and graduate students.