Manufacturing USA/GOALI: Visualizing Nanoscale Evolution during Aluminum Alloy Melt Processing

减轻在陆地、海上和空中运送人员和货物的车辆的重量对于提高燃油经济性和增加任务有效载荷至关重要。由于其高强度重量比，铝合金被用于汽车和航空航天工业，以满足这一需求。然而，为了提高燃油效率，需要更高强度和更轻重量的合金，这可以通过在铝基体中加入纳米级颗粒来实现。一种生产纳米颗粒的新方法是将气泡直接引入熔融铝中。将氮气吹入熔体中可以产生50纳米大小的氮化铝颗粒。该学术与工业联络资助机会（GOALI）奖支持基础研究，以提供控制颗粒尺寸和形状所需的知识，从而优化机械性能和性能。这项研究的结果将使工业界能够扩大这一过程，从小型实验室熔体到商业尺寸的铸锭，这将使开发用于地面、空中和海上运输的轻质合金成为可能，这对美国经济有直接的好处。参与这项研究的学生将有机会与来自行业的工程师互动，他们是团队的一部分。将采用实验与建模相结合的方法，形成材料工程教育的新基础。外联活动强调对妇女和代表性不足的少数民族的指导。50-200纳米颗粒的掺入可以提高铝合金的强度和高温稳定性。然而，由于纳米颗粒的团聚和纳米颗粒与基体界面的结合不足，复合材料的力学性能往往会下降。通过原位气液反应直接在熔融金属中生成增强纳米颗粒的新方法已被证明可以产生纳米级分散的AlN和TiC颗粒。在这个项目中，纳米到微观结构动力学控制的过程将进行研究。这些基础研究的见解将指导大规模原位铝纳米复合材料制造的工艺条件窗口的确定，从而产生具有最佳机械性能的纳米颗粒形态和分布。为了研究纳米尺度的热力学和动力学过程，将利用原位反射高能电子衍射（RHEED）技术在分子束外延（MBE）系统中进行合金氮化。为了原位三维纳米颗粒可视化，将开发一个微型熔体，并使用基于同步加速器的x射线纳米层析成像实现纳米复合材料的三维可视化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Reducing the weight of vehicles that move people and goods on land, sea and air is critical for improving fuel economy and increasing mission payload. Aluminum alloys are used in the automotive and aerospace industries to meet this need because of their high strength-to-weight ratio. For improved fuel efficiency, however, higher strength and lighter weight alloys are needed, and this can be achieved though the incorporation of nanosized particles in the aluminum matrix. A novel approach to producing the nanoparticles has been developed based on the introduction of gas bubbles directly into the molten aluminum. Blowing nitrogen gas into the melt can produce aluminum nitride particles that are 50 nanometers in size. This Grant Opportunities for Academic Liaison with Industry (GOALI) award supports fundamental research to provide the knowledge needed to control the particle size and shape which lead to optimized mechanical properties and performance. The results from this research will enable industry to scale up this process from small laboratory melts to commercial size ingots, which will enable the development of lightweight alloys for ground, air, and sea transportation, with direct benefit to the U.S. economy. The students involved in this research will have the opportunity to interact with the engineers from industry who are part of the team. An integrated experimental and modeling approach will be utilized, which is forming the new basis for materials engineering education. Outreach activities emphasize the mentoring of women and underrepresented minorities. The incorporation of 50-200 nanometer particles has been shown to improve the strength and high temperature stability of aluminum alloys. However, due to agglomeration of the nanoparticles and insufficient bonding at the nanoparticle-matrix interface, the mechanical properties of the composite material are often degraded. A new approach, in which the reinforcing nanoparticles are generated directly in the molten metal via an in-situ gas-liquid reaction has been shown to produce nanosized, dispersed AlN and TiC particles. In this project, the nano- to micro- structural dynamics governing the process will be investigated. Insights from these fundamental studies will guide the identification of a process condition window for large-scale in-situ aluminum nanocomposite manufacturing, which produces a nanoparticle morphology and distribution with optimum mechanical properties. To examine the nanometer-scale thermodynamic and kinetic processes, in-situ reflection high-energy electron diffraction (RHEED) will be utilized during alloy nitridation in a molecular-beam epitaxy (MBE) system. For in-situ 3D nanoparticle visualization, a mini-melter will be developed and 3D visualization of the nanocomposites will be achieved using synchrotron-based X-ray nanotomography.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.