Collaborative Research: Exploiting Nanoscale Interfaces to Enhance Bulk Mechanical Response of Additively Manufactured Boron Nitride Nanotube-Metal Composites

尽管金属的增材制造正在彻底改变材料和由它们制成的零件的设计，但测量的机械性能，如强度和韧性，表现出显着的分散性，导致不可预测和潜在的灾难性故障行为。该奖项支持基础研究，以阐明增材制造金属中的小百分比纳米填料如何增强机械性能，从而提高可靠性并实现广泛的工程应用。这一进展可能会改变3D打印技术，并增强美国的制造业竞争力。此外，这项研究将培养一批不同的研究生和本科生在材料设计，材料力学，以及多尺度实验和计算的多学科领域。研究结果也将成为一个新的系列讲座的基础上3D打印纳米复合材料作为未来的航空航天材料的K-12夏令营的学生。空洞缺陷的存在，降低材料的性能，并在材料中引入属性变化，是增材制造金属的固有弱点。为了克服这一限制，本研究旨在研究用氮化硼纳米管增强增材制造的铝基体，因为纳米管-金属界面处产生多尺度强化和增韧机制。在原位电子显微镜的帮助下，不同加工条件下的界面强度将通过嵌入增材制造的金属膜中的单个纳米管的纳米机械拉出来直接量化。通过实验无法获得的更精细的纳米管-金属界面细节，例如在纳米管-金属界面处形成的复杂反应产物，将通过密度泛函理论计算来表征。纳米管-基质界面特性以及加工过程中产生的基质孔隙率测量结果将被纳入代表性体积元素的有限元模型中，以进一步阐明增材制造纳米复合材料样品的失效机制。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Although additive manufacturing of metals is revolutionizing design of materials and the parts made from them, the measured mechanical properties, such as strength and toughness, exhibit significant scatter, leading to unpredictable and potentially catastrophic failure behaviors. This award supports fundamental research to elucidate how small percentages of nanofillers in additively manufactured metals enhance the mechanical properties, thus improving reliability and enabling widespread engineering use. This progress could transform 3D printing technologies and invigorate the manufacturing competitiveness of the United States. Additionally, this research will train a diverse group of graduate and undergraduate students in the multidisciplinary areas of materials design, mechanics of materials, as well as multiscale experiments and computations. The research results will also form the basis of a new lecture series on 3D-printed nanocomposites as future aerospace materials for K-12 summer camp students.The presence of voiding defects, which degrades material performance and introduces property variations within the material, is an inherent weakness of additively manufactured metals. To overcome this limitation, this research aims to investigate the reinforcement of additively manufactured aluminum matrices with boron nitride nanotubes because of the multiscale strengthening and toughening mechanisms emanating at the nanotube-metal interface. The interfacial strength under different processing conditions will be directly quantified by nanomechanical pull-out of individual nanotubes embedded within additively manufactured metal films, with the help of in situ electron microscopy. The finer nanotube-metal interfacial details that are not accessible by experiments, such as the complex reaction products formed at the nanotube-metal interface, will be characterized by density functional theory calculations. The nanotube-matrix interfacial properties together with matrix porosity measurements arising from processing, will then be incorporated into finite element models of representative volume element to further elucidate the failure mechanisms of the additively manufactured nanocomposite specimens.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.