Collaborative Research: Friction Stir Processing of Cast Metal Matrix Nanocomposites

将纳米颗粒掺入轻金属中，形成金属基纳米复合材料，可以显著增强其性能，对汽车、航空航天和其他需要轻质结构部件以实现高能效的行业产生巨大影响，这也意味着减少空气污染。然而，在金属凝固过程中，要实现纳米颗粒的良好分散和捕获是非常困难的。高温金属熔体中纳米颗粒的有效掺入也是一个严重的问题。在较低的温度下，搅拌摩擦工艺可以有效地分散轻质金属基纳米复合材料中的纳米颗粒。该奖项支持基础研究，以提供创建简单，新颖和可扩展的制造技术所需的知识，以推动金属基纳米复合材料的广泛应用。这项研究将吸引、留住和吸引来自弱势群体的学生。K-12学生/教师和行业合作伙伴将接触到新技术。将开发跨学科的课程材料，以培养研究生和本科生。该合作项目的目标是：(1)通过对加工过程中纳米颗粒在晶粒内运动和分散的系统实验研究，显著推进对轻量化金属基纳米复合材料中摩擦搅拌处理与纳米颗粒相互作用的基本理解。(2)通过研究纳米颗粒尺寸和形貌、纳米颗粒负载和工艺参数对纳米复合材料微/纳米结构演变和由此产生的力学性能的影响，了解加工-微观结构-性能之间的关系。实验研究的金属基纳米复合材料将通过半固态铸造和搅拌摩擦工艺相结合的方法制备，在相对低温下有效地将纳米颗粒掺入半固态，并在固态下分散纳米颗粒并细化微观结构，从而获得优异的性能。通过微纳材料分析工具，本研究将表征半固态合金中微纳结构、纳米颗粒的掺入和分布以及金属基纳米复合材料中纳米颗粒的搅拌摩擦分散。将进行拉伸和硬度（宏观、微观和纳米）测试，以表征搅拌摩擦处理前后纳米复合材料的机械性能。

Incorporation of nanoparticles into light metals, forming metal matrix nanocomposites, can lead to significantly enhanced properties to generate tremendous impacts in the automotive, aerospace, and other industries that demand lightweight structural components in order to achieve high energy efficiency, which also means less air pollution. However, it is very difficult to achieve a good dispersion and capture of nanoparticles during solidification of metals. Effective nanoparticle incorporation into high temperature metal melts also presents a severe problem. Friction stir processing can serve as a powerful tool to disperse nanoparticles in the lightweight metal matrix nanocomposites fabricated by semi-solid processing at a relatively low temperature. This award supports fundamental research to provide knowledge needed to create a simple, novel and scalable manufacturing technology to drive metal matrix nanocomposites toward widespread applications. The research will attract, retain, and engage students from under-represented group. K-12 students/teachers and industry partners will be exposed to the new technology. Interdisciplinary curriculum materials will be developed to train graduate and undergraduate students.The objectives of this collaborative project are to (1) significantly advance the fundamental understanding of how friction stir processing interacts with nanoparticles in lightweight metal matrix nanocomposites, fabricated by semi-solid casting route, through a systematic experimental study on the nanoparticle movements and dispersion inside the grains during processing, and (2) understand the processing-microstructure-properties relations by investigating the effects of nanoparticle size and morphology, nanoparticle loading, and processing parameters on the micro/nano-structural evolution and the resultant mechanical properties of the nanocomposites. The metal matrix nanocomposites for the experimental study will be fabricated through a combination of semi-solid casting and friction stir processing to effectively incorporate nanoparticles in semi-solid state at a relatively-low temperature and disperse nanoparticles and refine microstructures in solid state to achieve superior properties. Through micro/nano materials analysis tools, this study will characterize micro/nano-structures, nanoparticle incorporation and distribution in alloys at semi-solid state and the nanoparticle dispersion by friction stir processing in metal matrix nanocomposites. Tensile and hardness (macro, micro, and nano) tests will be conducted to characterize the mechanical properties of the nanocomposites before and after friction stir processing.