FRG: Fundamental Approaches to Design of New Magnesium Structural Alloys

技术：镁合金是所有结构合金中密度最低的，具有高的比强度，但必须开发新的合金以在150-250℃的使用温度范围内使用。在可用于汽车规模化生产的铸造工艺的限制下，识别在这些温度下提供强化和稳定性的新合金化方法仍然是一个关键的材料挑战。与其他结构合金系统相比，对潜在的高温镁合金系统的行为缺乏基本的了解，这被认为是在寻找新的轻质高温镁系统方面取得重大进展的关键障碍。为了解决这一问题，密歇根大学和威斯康星大学在福特汽车公司和通用汽车公司的大力合作下，启动了一个合作研究计划(FRG)。研究部分镁合金系统中凝固、相平衡和变形机制的基本认识方面的主要差距，以便为设计满足在高温下潜在使用的多种需求的合金奠定坚实的基础。这将通过：(1)选择可能在其上实施未来合金开发计划的有前途的系统，(2)通过建模和实验相结合的方式建立这些系统的完整热力学描述，(3)评估这些系统在实际铸造条件下的凝固行为的关键方面，以及(4)研究高温变形蠕变的机理。两个四元系，镁-铝-钙-锶和镁-铝-钙-钕，将最初推动这项研究，并将使我们能够在现有的学术和工业合作的基础上再接再厉。预期的结果包括：(1)定义改善蠕变性能的微观组织修改策略，(2)确定可用于改变凝固路径以进行关键微观组织控制的更高级别的元素添加，(3)改善晶界附近金属间化合物相稳定性的现实方法，(4)改进热力学描述和合金设计工具，以及(5)用于评估镁基系统的凝固和铸造行为的新的定量方法。非技术性：该研究计划旨在通过作为研究活动和大学/行业合作的核心，刺激更集中的国家对高温铸造镁合金的研究努力。该项目的本科生和研究生的教育经验将通过与工业人员的互动以及直接访问他们独特的研究设施，特别是福特汽车公司和通用汽车的研究设施而大大增强。核心协作小组的一个特别优势是密歇根大学和威斯康星大学彼此之间以及与美国汽车制造商(和供应商)的物理上的接近。该计划将使美国在轻质镁合金方面的学术活动更接近(但肯定不等同)亚洲和欧洲的观察研究水平。该计划还将加强密歇根州和威斯康星州MSE核心课程中的学术课程。最后，每年在密歇根大学举办的ASM国际高中教师夏令营将获得该项目与能源效率和轻质材料有关的资源。

TECHNICAL: Magnesium alloys have the lowest density among all structural alloys and possess high specific strength, but new alloys must be developed for use in the service temperature range of 150-250 C. The identification of new alloying approaches that provide strengthening and stability at these temperatures, within the constraints of casting processes that are viable for automotive-scale production, remains a critical materials challenge. The relative lack of fundamental understanding of the behavior of potential high temperature magnesium alloys systems, compared to that for other structural alloy systems, has been identified as a critical obstacle to significant progress in the search for new lightweight, high temperature magnesium systems. To address this a collaborative research program (FRG) between the University of Michigan and the University of Wisconsin, with strong collaboration from Ford Motor Company and General Motors is initiated. Key gaps in the fundamental understanding of solidification, phase equilibria and deformation mechanisms in selected magnesium alloy systems will be investigated in order to establish a strong foundation for the design of alloys that meet the multiple demands required for potential use at high temperature. This will be accomplished by: (1) selection of promising systems on which future alloy development programs are likely to be conducted, (2) establishment of full thermodynamic descriptions of these systems through a combined modeling and experimental effort, (3) evaluation of key aspects of the solidification behavior of these systems under realistic casting conditions and (4) investigation of mechanisms of high temperature deformation creep. Two quaternary systems, Mg-Al-Ca-Sr and Mg-Al-Ca-Nd, will initially motivate the research and will permit us to build on existing academic and industrial collaborations. Anticipated outcomes include (1) definition of microstructural modification strategies for improvement of creep properties, (2) identification of higher order elemental additions that can be used to alter solidification paths for critical microstructural control, (3) realistic approaches for improving the stability of intermetallic phases near the grain boundaries, (4) refined thermodynamic descriptions and alloy design tools and (5) new quantitative approaches for evaluation of solidification and casting behavior of Mg-based systems. NON-TECHNICAL: The research program is designed to stimulate a more concentrated national research effort on high temperature cast magnesium alloys, by serving as a nucleus of research activity and university/industry collaboration. The educational experience of the undergraduate and graduate students in the program will be greatly enhanced by interactions with industrial personnel as well as by direct access to their unique research facilities, particularly those of the Ford Motor Company and General Motors. A particular strength of the core collaborative group is the physical proximity of the University of Michigan and the University of Wisconsin to each other and to the U.S. automotive manufacturers (and suppliers). The program would bring the U.S. academic activity on lightweight Mg alloys closer (but certainly not equivalent) to observed levels of research effort in Asia and Europe. The program will also enhance academic courses within the core MSE curricula at both Michigan and Wisconsin. Finally, resources from this program relating to energy efficiency and lightweight materials will be made available to the ASM International High School Teachers Camp, which is hosted annually at the University of Michigan.