Materials World Network: Structures and Mechanical Behavior of Nanocrystalline Phase-Containing Glass-Forming Thin Films

材料世界网络奖由田纳西诺克斯维尔大学材料研究部的金属材料和纳米结构计划颁发，旨在建立对非晶态/纳米晶金属薄膜涂层的加工和制造以及由此产生的延展性和抗疲劳性能增强的机制的基本了解。该奖项由特别项目办公室(DMR)和国际科学与工程办公室共同资助。这项合作的实验和理论项目是由田纳西大学和中国共和国(台湾)的团队进行的，该团队由国立台湾科技大学、国立台湾海洋大学和国立成功大学组成。该项目的动机是两个新的和初步的观察结果，两个团队最近发现：1)无论是否存在纳米晶相，都可以通过退火诱导非晶化过程制备金属玻璃涂层；以及2)结构材料上的这些涂层显示出优异的机械性能和抗疲劳性能。在实验计划中，台湾团队将开发和改进实现退火过程中可控非晶化和纳米化的薄膜制备方法，美国团队将重点研究这些衬底上薄膜系统的变形和疲劳行为。先进的表征手段，如高分辨电子显微镜，将被用来研究(1)薄膜制备过程中的微结构演变和(2)在机械测试过程中应变局域化与金属玻璃薄膜中纳米晶相的相互作用。从建模的角度来看，台湾团队将侧重于退火非晶化动力学过程的分子动力学研究，而美国团队将致力于剪切带特性与薄膜力学行为之间的关系，以及薄膜对疲劳行为的影响。将这些模型与实验观测结果联系起来并与之比较，将有助于对疲劳机制的基本理解。合作研究将促进和加强美国和台湾方面的重点研究和教学活动。这一联合计划的研究项目将被设计并用作初中生和教师，特别是参与外展计划的妇女和少数民族学生的教学单位。这些努力不仅是为了提高公众对先进结构材料及其科学重要性的认识，也是为了激发更广泛的公众对科学、工程和技术事业的兴趣。将通过新开设的两个研究生级班级编写和传播教材。目前的综合研究和教育活动将提高公众对国际科学合作的认识。

This Materials World Network award by the Metallic Materials and Nanostructures program in the Division of Materials Research to University of Tennessee Knoxville is to establish a fundamental understanding of the processing and fabrication of amorphous/nanocrystalline metallic thin-film coatings, and the mechanisms responsible for the resulting ductility and fatigue-resistance enhancements. This award is cofunded by the Office of Special Projects-DMR and the Office of International Science and Engineering. This collaborative experimental and theoretical project is carried out between the University of Tennessee and the team in the Republic of China (Taiwan) consisting of National Taiwan University of Science and Technology, National Taiwan Ocean University and National Cheng Kung University. This project is motivated by two novel and preliminary observations that the two teams recently discovered that: 1) metallic-glass coatings with or without the presence of nanocrystalline phases can be prepared by an annealing-induced amorphization process; and 2) these coatings on structural materials demonstrate excellent mechanical properties and fatigue resistance. In the experimental program, the Taiwan team will develop and improve the thin-film preparation method that realizes the controllable amorphization and nanocrystallization during annealing, and the USA team will focus on the deformation and fatigue behavior of these film-on-substrate systems. Advanced characterization tools, such as the high-resolution transmission-electron microscopy, will be employed to study (1) the microstructural evolution during the thin-film preparation and (2) the interaction of the strain localization and the nanocrystalline phase in the metallic-glass film during mechanical testing. From the modeling point of view, the Taiwan team will emphasize a molecular-dynamics study of the kinetic processes in the annealing-induced amorphization, while the USA team will work on the relationship between the shear-band characteristics and the mechanical behavior of the film, and the effect of the film on the fatigue behavior. The connection of these models to and comparisons with the experimental observations will lead to the basic understanding of fatigue mechanisms. The collaborative research will advance and enhance the focused research and teaching activities on both the USA and Taiwan sides. Research projects from this joint program will be designed and used as a teaching unit for both middle- and high-school students and teachers, especially women and minority students involved in the outreach programs. These efforts are designed, not only to increase the public awareness of advanced structural materials and their scientific importance, but also to stimulate the interests of the broader public in science, engineering, and technology careers. Educational materials will be developed and disseminated through two newly-developed graduate-level classes. The present integrated research and education activities will promote the public awareness of the international-scientific collaboration.