GOALI: Additive Manufacturing of Nano-twinned Metals via Localized Pulsed Electrodeposition (L-PED)

加法制造通过允许从计算机模型逐层生产零部件，正在给制造业带来革命性的变化。与塑料、聚合物和水凝胶的3D打印相比，金属添加剂制造被工业采用的速度较慢。这一学术联系机会(GOALI)项目涉及能够扩大金属添加剂制造的基础研究。这项研究将使这一过程集中在一种特殊类型的金属上，称为“纳米孪晶”金属，这种金属同时表现出高强度、高延展性和高导电性。这些性能是由其特殊的微观结构实现的，这与传统金属截然不同。具体地说，在这些金属的原子结构中，特殊边界(孪生边界，TBS)的平行阵列形式，其中原子相对于边界具有镜像对称性。这些边界强化了金属。此外，电流可以很容易地流过边界中的镜像原子，使这些材料非常适合电气应用。这项基础研究将产生一种可在许多行业采用的附加制造工艺，例如用于结构应用、电子互连和传感器。这项研究可能会产生一种可行的商业低成本金属3D打印机，可以被学术研究实验室、教育机构和小型制造企业(SME)采用。在这个项目中，将对一种新的金属添加剂制造工艺进行基础研究，这种新工艺可以控制孪晶厚度和孪晶密度，从而控制机械和电气性能。该工艺基于局域脉冲电沉积工艺。纳米孪晶金属是超细晶或细晶金属，包含高密度的层状纳米区域。这些区域被连贯的孪生边界分开。纳米孪晶金属具有前所未有的超高强度、高延展性和高导电性的组合。这种块状金属可以通过各种方法合成，包括电沉积、再结晶、相变、溅射沉积和塑性变形处理。然而，目前还没有添加制造纳米孪晶金属的工艺。本项目将通过多物理模拟和多尺度实验相结合的方法，加深对局域脉冲电沉积(L-PED)制备纳米孪晶金属添加剂的理论理解。此外，还将利用三维L电子探针技术制备纳米孪晶金属，并对印刷金属的工艺-组织-性能关系进行研究。

Additive manufacturing is revolutionizing manufacturing by enabling layer-by-layer production of components from computer models. Metal additive manufacturing has been adopted by industry at a slower pace compared to 3D printing of plastics, polymers, and hydrogels. This Grant Opportunities for Academic Liaison with Industry (GOALI) project involves fundamental research to enable expansion of additive manufacturing of metals. The process enabled by this research will be focused on a specialized type of metals, called `nano-twinned' metals, which exhibit simultaneous high strength, high ductility, and high electrical conductivity. These properties are enabled by their special microstructure, which is distinctly different than conventional metals. Specifically, in the atomic structure of these metals, parallel arrays of specialized boundaries (twin boundaries, TBs) form in which atoms have a mirror symmetry with respect to the boundary. These boundaries strengthen the metal. Also, electric current can readily flow through mirror atoms in the boundary, making these materials well-suited for electrical applications. This fundamental research will result in an additive manufacturing process that can be adopted in many industries such as for structural applications, interconnects in electronics, and sensors. This research may result in a viable commercial low-cost 3D printer for metals, which can be adopted by academic research labs, educational facilities, and small manufacturing enterprises (SMEs). The partnership with industry on this GOALI project will facilitate such transition.In this project, fundamental research will be conducted on a new process for additive manufacturing of metals with controlled twin lamella thickness and twin density, and hence controlled mechanical and electrical properties. The process is based on a localized pulsed electrodeposition process. Nano-twinned metals are ultrafine-grained or fine-grained metals that contain a high density of layered nanoscale regions. These regions are divided by coherent twin boundaries. Nano-twinned metals have an unprecedented combination of ultrahigh strength, high ductility, and high electrical conductivity. This type of metal in bulk form can be synthesized via various approaches including electrodeposition, recrystallization, phase transformation, and sputter deposition, and plastic deformation processing. However, there is no current process for additive manufacturing of nano-twinned metals. This project will develop a theoretical understanding of additive manufacturing of nano-twinned metals by localized pulsed electrodeposition (L-PED) using combined multi-physics simulation and multi-scale experiments. In addition, nano-twinned metals will be manufactured by 3D L-PED and the process-structure-property relationship of the printed metals will be investigated.