Doctoral Dissertations

Abstract

"Laser powder-based directed energy deposition (DED) is a major laser aided additive manufacturing (AM) process for metals. It applies laser energy to deposit metal powders to form 3D metal parts. Apart from manufacturing traditional alloys, DED can also be used to develop advanced alloys with the novel idea of elemental powder mixture feedstock. TiNi-based alloy is a type of shape memory alloy (SMA), a smart material with unique shape memory effects. Using laser powder DED to synthesize TiNi-based SMAs from elemental powder mixture can create more possibilities in new compositions and properties. It can also overcome the limitations of conventional manufacturing.

In this work, a comprehensive review on applying elemental powder mixture in the DED process to fabricate all kinds of alloys was first performed to summarize the current status of this novel method. Then, the elemental powder DED process was used to deposit Ti–Ni–Cu ternary SMA with Cu as the third element to extend the application of DED in fabricating ternary SMAs. The major phase obtained was TiNi phase with successful shape memory effects. Next, Ti-rich Ti–Ni–Cu ternary SMA was fabricated on the substrate of near equiatomic TiNi binary SMA by the elemental powder DED process to build bi-metallic SMA structures with two different SMA sections and multiple shape memory effects. The joining region obtained a good quality, and the multiple shape memory temperatures were demonstrated. Heat treatment effects on material properties of the as-deposited bi-metallic Ti–Ni–Cu/TiNi SMA were also studied, and the various combinations of properties show that the DED process via elemental powder has great potential in developing multifunctional smart alloys with a wide range of applications"--Abstract, p. iv

Advisor(s)

Liou, Frank W.

Committee Member(s)

Chandrashekhara, K.
Dharani, Lokeswarappa R.
Midha, A. (Ashok)
Miller, F. Scott

Department(s)

Mechanical and Aerospace Engineering

Degree Name

Ph. D. in Mechanical Engineering

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2022

Pagination

xiv, 136 pages

Note about bibliography

Includes_bibliographical_references_(pages 132-135)

Rights

© 2022 Yitao Chen, All Rights Reserved

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 12307

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