Soft magnetic materials have been widely used in electric motors, routers, and detectors. Tremendous studies have been conducted to report microstructural features corresponding to magnetic performance. The laser-based powder bed fusion (L-PBF) additive manufacturing technique was implemented to bulk-scale fabricate the Finemet nanocrystalline magnetic alloy. This research study aims to reveal the capability of replacing the traditional melt spinning process with decent bulk density and magnetic properties. Nanocrystalline materials originate from optimizing amorphous metallic alloys, resulting in low coercivity and high saturation magnetization by facilitating the formation of nanocrystals. An extremely high cooling rate is the foundational factor for controlling the microstructure. Selective Laser Melting (SLM) offers a layer thickness of 20-100 µm, naturally providing a cooling rate of 105 - 107 K/s. Subsequent melting will impact the microstructure by conducting heat continuously through the melt pools. The relationship between microstructural features and crystalline phase characterization is discussed. Magnetic characterization, in terms of saturation magnetization and coercivity, with various processing parameters, is investigated. / Master of Science / Additive manufacturing of Finemet soft magnetic materials to approach expected microstructure and magnetic properties open up the path of replacing traditional manufacturing techniques. Freedom of complicated near net morphology design and inter-layer microstructural control by manipulating processing parameters offer revolutionary fabrication process comparing to traditional casting and welding. The magnetic performance of soft magnetic materials in real life applications such as electric motor is depending on multiple factors. Thus, the fascinating magnetic properties of soft magnetic materials owing strict requirement of microstructure and crystallite size. Aside from magnetic properties, as-printed bulk density fabricated by SLM would hugely impact the overall mechanical properties and porosity. Thus, processing parameters optimization through experiment and characterization would significantly benefit this study. Afterwards, comparison groups of samples with decent bulk density were taken into characterizations to reveal the crystalline phases, microstructure of metallic phases with respect to the melt pool morphology and then magnetic property of coercivity and saturation magnetization were carefully analyzed.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/116520 |
| Date | 20 October 2023 |
| Creators | Wang, Haozheng |
| Contributors | Materials Science and Engineering, Yu, Hang, Zuo, Lei, Cai, Wenjun, Reynolds, William T. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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