CAREER: Understanding Joining Mechanisms in Dissimilar Metal Additive Manufacturing

这项学院早期职业发展(Career)助学金专注于在不同合金之间建立牢固连接的研究，这是通过基于激光的添加剂制造或三维(3D)打印过程制造多合金部件的关键方面。这种方法实现了多功能部件，并在单个部件中结合了增强的性能。这些部件对国防、卫生、制造、航天和能源部门特别感兴趣，这些部门需要高质量、复杂和具有最理想性能的定制部件，这将影响美国的工业和经济。研究的目的是了解在送丝、送粉过程中混合金属和合金的激光熔化如何影响不同合金的连接，从而制造出无缺陷的异种金属部件。为了实现这一点，采用计算建模和实验处理的方法研究了熔化异种合金中的热和流体流动行为。这项研究使3D打印多材料组件中所需的特性能够在空间上变化。该项目旨在将研究与不同层次的学生，特别是妇女和代表性不足的少数群体的教学、指导和培训结合起来。为了支持艺术激发创造性思维的理念，该项目提供了包括基于艺术和STEM整合的实践活动的暑期项目，以鼓励K-12学生追求科学和工程领域。附加制造(AM)允许同时实现设计自由和在多材料部件的生产中融入空间变化的特性。研究的目的是全面了解添加剂制造过程物理对不同连接机制的影响。这是通过研究过程诱导混合在不同合金界面上的作用来实现的。中心假设是，混合生成的合金的微观组织直接受工艺诱导的混合程度的影响，而过程诱导的混合程度又取决于热流体流动和熔池的热历史。这一现象主要是由添加剂制造工艺参数和不同界面处的热物理性质的综合影响所驱动的。该研究框架将多尺度、多物理建模与激光送丝、送粉定向能沉积(DED)制备实验和显微组织分析相结合。此外，还建立了DFT和CALPHAD模型来分析不同熔池的热历史、组成和熔池尺寸。这些信息有助于确定不同金属添加剂制造中的特定连接机制，如双金属接头、成分梯度接头和过渡层接头。这项研究推动了添加剂制造领域的发展，以创造具有增强功能的创新的高性能多材料部件。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。

This Faculty Early Career Development (CAREER) grant focuses on research to create strong joints between dissimilar alloys, a critical aspect of making multi-alloy components through the laser-based additive manufacturing or three-dimensional (3D) printing process. This approach achieves multi-functional parts with enhanced properties combined in a single component. These components are of particular interest to defense, health, manufacturing, space, and energy sectors where high quality, complex, and customized parts with the most desired performance are needed, which impacts US industry and economy. The research goal is to understand how laser-melting of mixed metals and alloys in a wire-feed, powder-feed process affects the joining of different alloys towards the fabrication of defect-free dissimilar metal components. To achieve this, thermal and fluid flow behavior within the melted dissimilar alloys is studied using computational modeling and experimental processing. This research enables the desired properties in 3D printed multi-material components to be spatially varied. This project aims to integrate research with teaching, mentoring, and training of students at different levels, especially, women and underrepresented minorities. In support of the notion that the Arts activate creative thinking, the project offers summer programs involving hands-on activities based on Art and STEM integration to encourage K-12 students to pursue science and engineering fields.Additive manufacturing (AM) allows for the simultaneous achievement of design freedom and the incorporation of spatially varying properties in the production of multi-material components. The research objective is to gain a comprehensive understanding of the effects of additive manufacturing process physics on dissimilar joining mechanisms. This is achieved by investigating the role of process-induced mixing at the dissimilar alloy interfaces. The central hypothesis is that the microstructure of the mixing-resultant alloy is directly influenced by the degree of process-induced mixing, which, in turn, is governed by thermal fluid flow and thermal history of the melt-pool. This phenomenon is predominantly driven by the combined effects of additive manufacturing process parameters and thermo-physical properties at the dissimilar interface. The researched framework integrates multi-scale, multi-physics modeling with laser-based wire-feed, powder-feed directed energy deposition (DED) fabrication experiments and microstructural analysis. Additionally, DFT and CALPHAD models are created to analyze the thermal history, composition, and melt pool dimensions of the dissimilar melt-pools. This information aids in identifying the specific joining mechanisms in dissimilar metal additive manufacturing, such as bimetallic joints, compositional gradient joints, and transition layer joints. This research advances the field of additive manufacturing to enable the creation of innovative high performance multi-material components with enhanced functionality.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.