CAREER: Understanding Joining Mechanisms in Dissimilar Metal Additive Manufacturing

该学院早期职业发展（CAREER）资助的重点是研究在不同合金之间创建牢固的接头，这是通过基于激光的增材制造或三维（3D）打印工艺制造多合金部件的一个关键方面。这种方法实现了在单个组件中组合具有增强特性的多功能部件。这些组件对国防、健康、制造、空间和能源部门特别感兴趣，这些部门需要具有最理想性能的高质量、复杂和定制的部件，这对美国工业和经济产生了影响。研究目标是了解在送丝、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，以制造无缺陷的异种金属部件。为了实现这一点，热和流体流动行为内的熔融异种合金进行了研究，使用计算建模和实验处理。 这项研究使3D打印多材料组件的所需属性在空间上变化。该项目旨在将研究与教学、辅导和培训不同层次的学生，特别是妇女和代表性不足的少数民族相结合。为了支持艺术激活创造性思维的理念，该项目提供暑期项目，包括基于艺术和STEM融合的实践活动，以鼓励K-12学生追求科学和工程领域。增材制造（AM）允许同时实现设计自由和在多材料组件生产中纳入空间变化特性。研究目的是全面了解增材制造工艺物理对不同连接机制的影响。这是通过研究过程引起的混合在不同的合金界面的作用。中心假设是混合所得合金的微观结构直接受工艺诱导混合的程度影响，而工艺诱导混合的程度又受熔池的热流体流动和热历史的影响。这种现象主要是由增材制造工艺参数和不同界面处的热物理性质的组合效应驱动的。研究框架集成了多尺度，多物理建模与基于激光的送丝，送粉定向能量沉积（DED）制造实验和微观结构分析。此外，DFT和CALPHAD模型被创建来分析不同熔池的热历史、成分和熔池尺寸。该信息有助于识别异种金属增材制造中的特定连接机制，例如双金属接头、成分梯度接头和过渡层接头。该研究推动了增材制造领域的发展，从而能够创造出具有增强功能的创新型高性能多材料组件。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.