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Directed Energy Deposition of Ni-Mn-Ga Magnetic Shape Memory Alloy

Toman, Jakub (2017) Directed Energy Deposition of Ni-Mn-Ga Magnetic Shape Memory Alloy. Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

Processing of magnetic shape memory alloys – active materials that show strains of up to 12 % in a magnetic field and that are being targeted for application as actuators, sensors and energy harvesters – suffers from challenges including time intensive production and macrosegregation that leads to reduced yield. Furthermore, the brittle mechanical behavior of these materials largely eliminates the possibility of machining for a desired shape. This work explores directed energy deposition, an additive manufacturing or “3D printing” process, as an alternative processing route for Ni Mn Ga magnetic shape memory alloy. The magnetic properties, transformation behavior, and composition of the feedstock powder and deposits resulting from a laser metal deposition process are investigated against varied laser power. All samples are seen to possess favorable magnetic behavior and potentially favorable phase for magnetic field induced strain (MFIS) to take place. Additionally, the microstructure of the deposited samples is observed and its special features that may aid MFIS are discussed. Most notably, this thesis presents possible evidence of twin variants crossing deposition layers and of twin boundary motion in a magnetic field. Finally, a connection between lower laser power and reduced loss of Mn is considered.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Toman, Jakubjat141@pitt.edujat1410000-0001-7083-0163
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairChmielus, Markuschmielus@pitt.edu
Committee MemberNettleship, Iannettles@pitt.edu
Committee MemberTo, Albertalbertto@pitt.edu
Date: 1 February 2017
Date Type: Publication
Defense Date: 17 November 2016
Approval Date: 1 February 2017
Submission Date: 15 November 2016
Access Restriction: 3 year -- Restrict access to University of Pittsburgh for a period of 3 years.
Number of Pages: 131
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: magnetic shape memory alloy, MSMA, ferromagnetic shape memory alloy, FSMA, Heusler alloy, additive manufacturing, AM, 3D printing, laser metal deposition, LMD, directed energy deposition, DED, laser engineered net shaping, LENS, processing, rapid solidification
Date Deposited: 01 Feb 2017 17:55
Last Modified: 01 Feb 2020 06:15
URI: http://d-scholarship.pitt.edu/id/eprint/30306

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