Date of Award

6-2025

Degree Name

Master of Science

Department

Mechanical and Aerospace Engineering

First Advisor

Pnina Ari-Gur, D.Sc.

Second Advisor

Matthew Cavalli, Ph.D.

Third Advisor

Jinseok Kim, Ph.D.

Access Setting

Masters Thesis-Open Access

Abstract

A traditional cooling system, which applies compression technology within the working fluid, has had a lot of negative impacts on the environment and has low efficiency. They have almost reached the thermodynamic efficiency; there is little room for further improvement. Therefore, solid-state cooling systems, especially those that use the magnetocaloric effect (MCE), have drawnmuch interest as an alternative solution for the vapor-compression system. The Heusler alloy, especially Ni-Mn-In in this research, can be an excellent candidate for this application due to its unique properties, such as the shape memory effect and giant MCE. Their giant MCE results from a first-order magnetostructural martensitic transformation between low-temperature martensite and high-temperature austenite. When the crystalline and magnetic phase transformations coincide, the giant MCE is largest. The manufacturing process and chemical composition are important in these alloys' magnetic properties and crystal structure. In this research work, all four samples were made using a melt-spinning technique. They are designated as BMS534 (Ni40.6Mn34.8In24.4), BMS535 (Ni42.4Mn26.8In31.5), BMS563 (Ni44.9Mn438In12.1), and BMS564 (Ni50Mn34In16). BMS563 and BMS564 were later heat-treated under two different conditions to observe the change in phase transformation. The X-ray diffraction technique (XRD) is used on these samples to analyze the crystal structures, phase fractions, and atomic site occupancies. The Rietveld Refinement technique is used to optimize the data collected from the XRD and differentiate the samples’ properties, especially when comparing the melt-spun version to a bulk version. The Superconducting Quantum Interference Device (SQUID) measurements were also conducted to see the magnetic properties within each composition.

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