Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 148043

148043 - Understanding Joining Mechanism in Dissimilar Metal Additive Manufacturing 

A robust dissimilar metal joint is crucial for the successful fabrication of multi-material components using additive manufacturing (AM). These components offer a promising alternative to meeting high-performance alloy requirements and present a novel solution to a longstanding challenge in materials science, where traditional manufacturing relied on single homogeneous alloys to meet all demands. For instance, incorporating Cu-based posts within a Ni-based heat exchanger can significantly enhance its efficiency and reduce both its size and mass by leveraging vectorized thermal conductivity. However, the current literature primarily focuses on avoiding the formation of deleterious phases in dissimilar systems, employing compositional gradient pathways, without fully correlating these approaches to the physics of the AM process. Consequently, the mechanisms behind dissimilar metal AM joints remain inadequately understood, with insufficient insights into process physics, interface characteristics, and laser-matter interactions at the interfaces. This research proposal aims to comprehensively understand the impact of AM process physics on dissimilar joining mechanisms. The central hypothesis posits that the microstructure of the dissimilar melt pool is directly influenced by the level of process-induced mixing, which, in turn, is governed by thermal fluid flow and thermal history. The interplay of AM process parameters and thermo-physical properties at the interface predominantly drives this phenomenon. I propose a framework that integrates multi-scale, multi-physics modeling with experimental fabrication and characterization techniques to achieve this objective.

 This work aims to develop an experimental and computational framework to investigate the role of AM process physics in dissimilar joining mechanisms. For the first time, strategies will be devised to predict and validate thermal diffusivity and thermal fluid flow within the dissimilar melt pool. Further, models will be created to analyze dissimilar melt pools' thermal history, composition, and dimensions. This information will aid in identifying the specific joining mechanisms in dissimilar metal AM. Building upon these strategies, the goal is to fabricate bimetallic joints, compositional gradient joints, and transition layer joints using corresponding AM process parameters. This study will lay the groundwork for understanding the physics behind dissimilar metal joining through AM processes. It will enable the fabrication of well-designed joints with minimal defects by dictating process parameters based on the predicted and validated thermal properties and fluid flow characteristics within the melt pool of dissimilar materials. Ultimately, this research holds great potential to advance the field of AM and enable the creation of innovative multi-material components that meet stringent performance requirements while offering increased efficiency and enhanced functionality.

The broader impacts include integrating the components of Fine Arts and STEM educational activities, and engagement of URMs in the AM workforce. Additionally, research skills and tools will be incorporated into both undergraduate and graduate courses taught by PI. A fundamental understanding of the underlying physics and corresponding joining and/or failure mechanisms in dissimilar metal systems will enable digital microstructure-property control in order to guide and implement AM of multi-material components. These components are of particular interest to defense, health, manufacturing, and energy sectors.

Presenting Author: Somayeh Pasebani Oregon State University

Presenting Author Biography: Dr. Somayeh Pasebani was hired as an assistant professor of advanced manufacturing in the School of Mechanical, Industrial, and Manufacturing Engineering (MIME) in September 2016. She was promoted to associate professor in 2023. She has been engaged in as a PI or co-PI is over $12 M of which her share was ~$3.4 M. Currently, she is managing >$2.6 M research grants (sponsored by NSF, DOE and AFRL). Dr. Pasebani is currently leading an NSF CAREER grant focused on multi-material additive manufacturing. Her research activities have led to 40 peer-reviewed publications in high-impact factor journals since joining OSU and all with her student advisees.

Authors:

Somayeh Pasebani Oregon State University