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Structural change in Ni-Fe-Ga magnetic shape memory alloys after severe plastic deformation
Published in MDPI AG
2019
Volume: 12
   
Issue: 12
Abstract
Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) was applied in the as-cast state. The exerted key parameters of deformation are described. Microstructural changes, including morphology that were the result of processing, were investigated by optical and scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to study the two-phase microstructure of the alloys. The influence of deformation on microstructural features, such as martensitic plates, intragranular phase precipitates, and grain boundaries' dependence of the extent of deformation is disclosed by transmission electron microscopy. Moreover, the work brings to light the influence of deformation on the characteristics of martensitic transformation (MT). Vickers hardness measurements were carried out on disks obtained by SPD so as to correlate the hardness with the microstructure. The method represents a feasible alternative to obtain ultrafine-grained bulk Ni-Fe-Ga alloys. © 2019 by the authors.
About the journal
JournalMaterials
PublisherMDPI AG
ISSN19961944
Open AccessYes
Concepts (23)
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    Energy dispersive spectroscopy
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    Ferromagnetic materials
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    Ferromagnetism
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    Gallium alloys
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    Grain boundaries
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    High resolution transmission electron microscopy
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    MAGNETIC SHAPE MEMORY
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    Martensitic transformations
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    Microstructure
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    Morphology
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    Nickel alloys
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    Plastic deformation
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    Scanning electron microscopy
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    SHAPE-MEMORY ALLOY
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    Ternary alloys
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    Torsional stress
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    VICKERS HARDNESS
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    Ferromagnetic shape memory alloy
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    HSHPT
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    NI-FE-GA
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    SEVERE PLASTIC DEFORMATIONS
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    ULTRAFINE GRAINED MATERIALS
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    Iron alloys