GOALI: Exploring In Situ Nanoparticle Synthesis and Redistribution during Solidification of Metal Matrix Nanocomposites

汽车和航空航天工业需要轻质、高强度的材料来减轻移动人员和货物的机器的重量，同时保持其完整性。铝合金满足了这一需求，因为它们具有高强度重量比。在铝中加入纳米颗粒使其在高温下更坚固和更稳定。只有当纳米颗粒不团聚并均匀分布在铝基质中时，才能实现这些改进。这一学术与工业联系机会(GOALI)奖旨在提供所需的基本知识，以控制粒子的重新分布而不结块。通过实时观察凝固过程，量化纳米颗粒的运动，并开发预测模型，研究人员计划对有利于均匀颗粒分布的工艺条件有新的理解。研究结果使工业能够将金属基纳米复合材料加工扩大到商业尺寸的铸件。此外，更坚固和更轻的材料可以实现更高的燃油经济性。这些因素有利于美国经济和社会。学生从与团队中的行业合作伙伴的合作中受益。外联活动吸引女性和代表性不足的少数族裔学生从事材料研究、加工和制造。金属基纳米复合材料(MMNC)与微型复合材料和整体合金相比，具有重量轻、强度高、耐磨性好和高温稳定性好等优点。然而，只有在纳米颗粒均匀分布的情况下，才能充分实现MMNCs力学性能的增强。在MMNCs的凝固过程中，凝固前沿附近的颗粒可能会被推进或吞没，从而影响纳米颗粒在凝固组织中的最终分布。该项目全面了解了颗粒在凝固过程中的再分布，特别是颗粒大小、流体流动以及凝固前沿速度和形态之间的相互关系。为此，该团队将熔体加工、实时计量和相场模拟方面的紧急研究联系起来，研究由聚合物前驱体原位合成纳米颗粒及其在金属基纳米复合材料凝固过程中的再分布。该团队研究了由行业合作伙伴Eck Industries提供的一系列颗粒大小和形状的MMNC样品；通过实时X射线成像实验可视化这些样品中纳米颗粒与凝固前沿之间的相互作用；并使用实验数据进行相场模拟，以获得关于颗粒推动-吞没转变的详细见解。这一综合努力有助于建立形态相图，最终能够精确控制MMNC的AS固化微观结构。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Automotive and aerospace industries require lightweight, high strength materials to reduce the weight of the machines that move people and goods while maintaining their integrity. Aluminum alloys meet this need because of their high strength-to-weight ratio. The incorporation of nanosized particles in aluminum makes it stronger and more stable at elevated temperatures. These improvements can only be achieved if the nanoparticles do not agglomerate and are uniformly distributed in the aluminum matrix. This Grant Opportunities for Academic Liaison with Industry (GOALI) award aims to provide the fundamental knowledge needed to control the redistribution of particles without agglomeration. By watching the solidification process as it unfolds in real-time, quantifying the motion of the nanoparticles, and developing predictive models, the researchers plan to achieve new understanding on the processing conditions that favor a uniform particle distribution. The research results enable industry to scale-up metal matrix nanocomposite processing to commercial size castings. In addition, stronger and lighter materials enable greater fuel economy. These factors benefit U.S. economy and society. Students gain from collaboration with industry partners on the team. Outreach activities engage female and under-represented minority students in materials research, processing and manufacturing. Industry collaborator North American Die Casting Association disseminates the results to industry.Metal matrix nanocomposites (MMNCs) offer light-weighting, improved strength, wear resistance, and high temperature stability compared to microcomposites and monolithic alloys. However, only with a homogeneous distribution of nanoparticles can the enhanced mechanical properties of MMNCs be fully realized. During solidification of MMNCs, the particles near the freezing front may be pushed or engulfed, thus impacting the final distribution of nanoparticles in the as-solidified microstructure. This project develops a comprehensive understanding of the redistribution of particles during solidification, specifically the interrelationships between particle size, fluid flow, and solidification front velocity and morphology. For this purpose, the team bridges emergent research in melt processing, real-time metrology, and phase field simulation to study in situ nanoparticle synthesis from polymer precursors and their redistribution during solidification of metal matrix nanocomposites. The team studies MMNC samples with a range of particle sizes and shapes provided by industry collaborator Eck Industries; visualizes the interactions between the nanoparticles and the solidification front in these samples via real-time X-ray imaging experiments; and conducts phase field simulations using the experimental data as input to yield detailed insights on the particle pushing-engulfment transition. This integrated effort helps to establish a morphological phase diagram, ultimately enabling precise control of the as solidified microstructure of MMNCs.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.