Sargent, Noah
(2024)
Integrated Computational and Experimental Design of Functionally Graded Materials Made with Additive Manufacturing.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Using the directed energy deposition (DED) additive manufacturing (AM) process, functionally graded materials (FGMs) are manufactured by dynamically controlling the feedstock composition, yielding one-piece multi-material components with location-specific properties. The development of FGMs has enabled new technological capabilities and an improved understanding of the underlying process-structure-property relationships in AM. The goal of this dissertation is to develop CALPHAD-based ICME (CALPHAD: CALculation of PHAse Diagrams, ICME: Integrated Computational Materials Engineering) models and experimental methods for designing defect-free FGMs and developing new alloys specifically designed for AM. Contributions to the framework for modeling FGMs include the prediction of solidification cracking susceptibility and a simple approach for modeling diffusion in complex multi-component composition gradients. The modeling framework is then integrated with high-throughput FGM experiments to discover novel AM alloys, leading to the discovery of microsegregation-aided transformation and twinning-induced plasticity in low-manganese steel. This discovery provides a new pathway for achieving transformation and twinning-induced plasticity effects in steel without heat treatment. Additional alloy development efforts aim to address the isotropic properties of AM alloys by employing powder-based directed energy deposition of FGMs to reveal new relationships between composition, processing, heat treatment, and grain refinement. Next, a successful processing and heat treatment strategy for Inconel 718 and stainless steel 316L FGMs is developed. The mechanical properties of the post-processed Inconel 718 and stainless steel 316L FGM exceed those previously reported in the literature. Further investigation of the microstructural stability and oxidation performance of Inconel 718 and stainless steel 316L under cyclic oxidation at elevated temperatures improves the understanding of FGMs operating in extreme environments. This dissertation presents an integrated computational and experimental design approach for multi-material AM. Leveraging computational tools and high-throughput experiments using FGMs, novel AM alloys, and new process-structure-property relationships are discovered. The contributions of this dissertation have implications for industries seeking to enhance the functionality of AM components while reducing costs, enabling more reliable and efficient solutions using multi-material additive manufacturing.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
11 January 2024 |
| Date Type: |
Publication |
| Defense Date: |
22 August 2023 |
| Approval Date: |
11 January 2024 |
| Submission Date: |
14 August 2023 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
156 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering and Materials Science |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Additve Manufacturing
Functionally Graded Materials
CALPHAD
Alloy Design
ICME |
| Additional Information: |
This the final version of my disseration approved by commitee and reviewed by the ETD office once. |
| Date Deposited: |
11 Jan 2024 19:27 |
| Last Modified: |
11 Jan 2024 19:27 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45339 |
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