CAREER: Understanding thermal phase change processes in metal additive manufacturing

职业：了解金属增材制造中的热相变过程

• 批准号: 2047123
• 负责人: Patricia Weisensee
• 金额: $ 55.66万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2047123&HistoricalAwards=false
• 关键词: CAREER; Understanding; thermal; phase; change

Laser-based additive manufacturing, including 3D metal printing, has revolutionized manufacturing processes by allowing manufacturers to make parts with complicated shapes that can be highly customized and making it possible to incorporate patterns of composition and micro-structure that may ultimately lead to new classes of materials and applications. Yet widespread implementation of additive manufacturing is limited by both technical issues, such as lack of quality control and part-to-part repeatability, and societal factors, such as the readiness of the engineering workforce. Mechanical properties, such as strength, hardness, and fatigue resistance – important quantities for any load-bearing component - are dictated by the material microstructure. These material properties are, in turn, governed by the details of the process: laser characteristics, the behavior of melted material, solidification, and the temperature of the workpiece over time. The opacity of metal has previously limited the ability to study the behavior of the melted material and the mechanism of solidification. Through an innovative research and educational approach, this project addresses challenges in implementing additive manufacturing, both the technical aspects, including microstructure and defect control, and the workforce development, laying the foundation for the broad implementation of robust and reliable additive processes.The scientific focus of this interdisciplinary project is to provide a comprehensive understanding of the thermal processes governing powder melting, convective mixing, and solidification in laser-based additive manufacturing of compositionally graded metals. Ex-situ experiments using an optically transparent surrogate system enable the characterization of phase change and fluid mixing. Based on preliminary experiments, two scenarios will be highlighted: i) the influence of powder impact location on melting and mixing, and ii) melting, mixing, and solidification of dissimilar materials. Using a unique in-situ high-speed thermal infrared imaging setup, capable of capturing transient events within the melt pool at the millisecond time scale, solidification dynamics in the transition zone of two metals will be quantified. Correlation of ex-situ and in-situ measurements along with post-deposition material characterization has the potential to lead to transformative advancements in additive manufacturing by creating a fundamental framework to couple process parameters with microstructural and defect development. Leveraging the fascination of 3D printing, educational activities aim at broadening and deepening participation of young people in science and engineering. At the core of these activities is the development of a 3D chocolate printer, which integrates hands-on scientific learning experiences with the appeal of high-speed imaging with different learning modules for both K-12 and undergraduate students. A specific focus is on empowering middle-school aged girls to pursue careers in STEM by providing a fun and low-stake introduction to additive manufacturing and thermal-fluid sciences.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.

基于激光的增材制造，包括3D金属打印，通过允许制造商制造具有复杂形状的部件，使其能够高度定制，并使其能够结合成分和微观结构的图案，最终可能导致新的材料和应用类别，彻底改变了制造工艺。然而，增材制造的广泛实施受到技术问题和社会因素的限制，例如缺乏质量控制和零件间的可重复性，例如工程人员的准备程度。机械性能，如强度、硬度和抗疲劳性--对于任何承载部件都是重要的参数--由材料的微观结构决定。这些材料特性反过来又受工艺细节的影响：激光特性、熔化材料的行为、固化以及工件随时间的温度。金属的不透明性以前限制了研究熔融材料的行为和凝固机制的能力。通过创新的研究和教育方法，该项目解决了实施增材制造的挑战，包括技术方面，包括微观结构和缺陷控制，以及劳动力发展，为广泛实施强大和可靠的增材工艺奠定了基础。这个跨学科项目的科学重点是全面了解控制粉末熔化的热过程，对流混合和成分梯度金属的基于激光的增材制造中的固化。使用光学透明的替代系统的非原位实验能够表征相变和流体混合。基于初步的实验，两个方案将突出显示：i）粉末碰撞位置对熔化和混合的影响，和ii）不同材料的熔化，混合和固化。使用一个独特的原位高速热红外成像装置，能够捕捉瞬态事件内的熔池在毫秒的时间尺度，凝固动力学在过渡区的两种金属将被量化。非原位和原位测量的相关性沿着与沉积后材料表征具有通过创建将工艺参数与微观结构和缺陷发展耦合的基本框架来导致增材制造的变革性进步的潜力。利用3D打印的魅力，教育活动旨在扩大和深化年轻人对科学和工程的参与。这些活动的核心是开发3D巧克力打印机，该打印机将实践科学学习经验与高速成像的吸引力结合起来，为K-12和本科生提供不同的学习模块。该奖项的一个特别重点是通过提供一个有趣和低风险的增材制造和热流体科学介绍，使中学年龄的女孩能够从事STEM职业。该奖项反映了NSF的法定使命，并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，被认为值得支持。