Collaborative Research: Friction Stir Processing of Cast Metal Matrix Nanocomposites

在轻金属中加入纳米颗粒，形成金属基纳米复合材料，可以显著增强性能，在汽车、航空航天和其他需要轻质结构部件以实现高能源效率的行业中产生巨大影响，这也意味着更少的空气污染。然而，在金属凝固过程中，很难实现纳米粒子的良好分散和捕获。在高温金属熔体中有效地加入纳米颗粒也是一个严重的问题。搅拌摩擦工艺可以作为一种强有力的工具，在较低温度下制备的轻质金属基纳米复合材料中分散纳米颗粒。该奖项支持基础研究，以提供所需的知识，创造一种简单、新颖和可扩展的制造技术，推动金属基纳米复合材料走向广泛应用。这项研究将吸引、留住和吸引来自代表性不足群体的学生。K-12学生/教师和行业合作伙伴将接触到这项新技术。这一合作项目的目标是：(1)通过对纳米颗粒在加工过程中在颗粒内的运动和分散进行系统的实验研究，显著提高对半固态铸造法制备的轻质金属基纳米复合材料中纳米颗粒与摩擦搅拌过程相互作用的基本理解；(2)通过研究纳米颗粒的尺寸和形貌、纳米颗粒的含量和工艺参数对纳米复合材料微/纳米结构演变和所产生的力学性能的影响，了解加工-微观结构-性能的关系。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来制备，以在较低的温度下有效地在半固态中融入纳米颗粒，并在固态中分散纳米颗粒和细化组织，以获得优异的性能。本研究将通过微纳米材料分析工具，对金属基纳米复合材料中的微纳米结构、纳米颗粒在半固态合金中的掺入与分布以及搅拌摩擦过程中纳米颗粒的分散情况进行表征。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.