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Investigation of Ni2MnGa-based shape memory alloys

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posted on 2018-08-07, 13:50 authored by Kristin Frohlich
Compounds with the general composition Ni2+xMn1-xGa belong to the group of ferromagnetic shape memory alloys. These materials have recently attracted a considerable amount of interest due to their potential for applications. Ferromagnetic shape memory alloys, in contrast to conventional shape memory materials, offer the possibility to initiate a change of shape with the application of an external magnetic field of modest magnitude in addition to shape changes induced via a shift in temperature. In this thesis the magnetic and crystallographic properties of Ni2+xMn1-xGa alloys are investigated within the range 0 < x < 0.17. Structural investigations using both X-ray as well as neutron scattering have been carried out. The low temperature phase has been determined and structural information has been obtained within the transition region for the first time. Magnetic properties have been investigated using a SQUID magnetometer within the temperature range of T = 2 K to 360 K and using magnetic fields up to 5.5 Tesla. The locations of phase transitions were investigated using DSC and resistivity measurements for both heating as well as cooling. The composition dependence of the martensitic and ferromagnetic transition temperatures have been confirmed. The first order nature of the martensitic phase transformation has been confirmed in DSC, magnetisation and resistivity measurements.

Funding

Friedrich Naumann Stiftung.

History

School

  • Science

Department

  • Physics

Publisher

© Kristin Fröhlich

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2004

Notes

A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy at Loughborough University.

Language

  • en

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