Doctoral Dissertations

Yiyu Shen

Keywords and Phrases

Additive Manufacturing; Crystallization; Laser Material Processing; Metallic Glass; Nucleation And Growth

Abstract

"The required rapid cooling has limited the dimension of the Bulk Metallic glasses (BMGs) produced by traditional method, and hence has seriously limited their applications, despite their remarkable mechanical properties. In this present project, a detailed study is conducted on the methodology and understanding of manufacturing large Zr- based metallic glass part by laser based additive manufacturing technology, which breaks the size limitation. The first research issue proposes and develops a new additive manufacturing technology, named Laser-Foil-Printing (LFP). Sheet foils of LM105 (Zr52.5Ti5Al10Ni14.6Cu17.9 (at. %)) metallic glass are used as feed stork. Fully amorphous 3D structures are successfully achieved. The second research issue focus on investigating the temperature evolution during laser-BMG interaction. By combining experimental measurement and mathematical model, the dynamic temperature field evolution during laser-BMG interaction is simulated. The developed model not only optimizes the LFP process, but also helps us in further understanding the fundamental crystallization mechanism during laser-BMG interaction. The crystalline phase evolution during laser-MG interaction is studied in the third research issue, using the classical nucleation theory (CNT). Combining with the temperature model, the volume fraction of crystallized BMG is calculated. The result successfully explains the observation of crystalline phase within both the fusion zone (FZ) and the heat-affected-zone (HAZ) of laser processed BMG. This thesis is a proven road map for developing metallic glass structures using additive manufacturing technology. The research results of this dissertation can benefit a wide range industry, such as 3D printing, material science, medical and aerospace"--Abstract, page iv.

Advisor(s)

Tsai, Hai-Lung

Committee Member(s)

Leu, M. C. (Ming-Chuan)
Okafor, A. Chukwujekwu (Anthony Chukwujekwu)
Pan, Heng
Story, J. Greg

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Sponsor(s)

United States Department of Energy
University of Missouri (System)
Missouri University of Science and Technology. Intelligent Systems Center

Comments

Financial support of the Department of Energy (Grant Number: DE-FE0012272) and University of Missouri System (award number Fast Track-16002R)

Research Center/Lab(s)

Intelligent Systems Center

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2018

Journal article titles appearing in thesis/dissertation

  • 3D printing of large, complex metallic glass structures
  • Evolution of crystalline phase during laser processing of Zr-based metallic glass
  • The effect of pre-existing nucleus density on crystallization behavior during laser processing of Zr-based metallic glass and the corresponding quality factor
  • The effect of overlap on crystallization of bulk metallic glass during additive manufacturing

Pagination

xi, 139 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2018 Yiyu Shen, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11317

Electronic OCLC #

1041858658

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