Martensitic transformation and accompanying magnetic changes in Ni–Fe–Ga–Co alloys

Sofronie, M.; Ţolea, Felicia; Kuncser, V.; Văleanu, M.

doi:10.1063/1.3429231

Cited by 18 publications

(5 citation statements)

References 21 publications

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“…For the LG ribbons with a more stable composition, the TT2 promote a slight increase of the Curie temperature as effect of the structure refinement and atomic ordering. In addition, it is observed the largest magnetization drop during the martensitic transformation, reflecting higher magnetocrystalline anisotropy of martensite [19] Surprisingly, but also attesting the accuracy of the magnetic measurements, the thermomagnetic measurements reveal the martensitic transformation even on the ribbons subjected to in situ DSC scans. The very large thermal hysteresis, obtained for VLG and LG samples after DSC scans extended over 100 degrees, may be due to precipitation of secondary phases, compositional inhomogeneities or crystallite size reduction.…”

Section: Magnetometry Datamentioning

confidence: 58%

“…The calorimetric scans ( Fig.1) reveal that TTs induce, aside from changes of the transformation heat (associated with the DSC peak area), a decrease of the MT temperatures, as more pronounced as the temperature and the duration of the TT increases. The thermograms for the bulk alloys are also included for comparison [19,20]. As a general trend it is observed that for higher Ga content, the MT temperature is less influenced by the thermal treatment.…”

Section: Calorimetry Datamentioning

confidence: 99%

See 1 more Smart Citation

Effect of thermal treatments on the structural and magnetic transitions in melt-spun Ni-Fe-Ga-(Co) ribbons

Ţolea

Sofronie

Crisan

et al. 2015

Journal of Alloys and Compounds

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Section: Magnetometry Datamentioning

confidence: 58%

Section: Calorimetry Datamentioning

confidence: 99%

Effect of thermal treatments on the structural and magnetic transitions in melt-spun Ni-Fe-Ga-(Co) ribbons

Ţolea

Sofronie

Crisan

et al. 2015

Journal of Alloys and Compounds

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“…In the present study, we examine the superelastic properties and the stress-induced martensite stabilization in a single crystal of NiFeGaCo FSMA with composition which is not prone to showing a second-phase precipitation [29,30]. The stress-strain measurements have been systematically performed on the sample cut along <110> A crystallographic axis of the cubic austenite since the deformation in this direction is crucial for obtaining a giant rubber-like behavior in an SIM-aged conditioned martensitic state [19], or developing a two-way SME [14], or modifying a character of the thermally induced strain recovery in such FSMAs [31].…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependent Stress–Strain Behavior and Martensite Stabilization in Magnetic Shape Memory Ni51.1Fe16.4Ga26.3Co6.2 Single Crystal

Lázpita,

Villa,

Villa

et al. 2021

Metals

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The superelastic properties and stress-induced martensite (SIM) stabilization have been studied in a shape memory Ni51.1Fe16.4Ga26.3Co6.2 single crystal. The single crystal, characterized by a thermally induced forward martensitic transformation temperature around 56 °C in the initial state, has been submitted to compression mechanical testing at different temperatures well above, near and below the martensitic transformation (MT). After each mechanical test, the characteristic MT temperatures and the transformation enthalpy have been monitored by means of differential scanning calorimetry. At temperatures below MT, the stress–strain (σ–ε) curves show a large strain, around 6.0%, resulting from the detwinning process in the martensitic microstructure, which remains accumulated after unloading in the detwinned state of the sample as a typical behavior of the shape memory alloys (SMAs). After just two “σ–ε + heating” cycles the accumulation of strain was not observed any more indicating the formation of a two-way shape memory effect which consists in a spontaneous recovery of the aforementioned detwinned state of the sample during its cooling across the forward MT. Whereas the thermally induced shape recovery in conventional SMAs occurs at the fixed value of the reverse MT temperature, the heating DSC curves of the mechanically deformed martensite in the present work show a burst-like calorimetric peak at the reverse MT arising at temperatures essentially higher than the thermally activated one. This behavior is the result of the SIM stabilization effect. After a short thermal aging in the stress-free state, this effect almost disappears, showing a slight impact on the MT characteristic temperatures and the enthalpy. At temperatures higher than the transformation one, the SIM is not stabilized, as the mechanically induced martensite fully retransforms into austenite after the unloading. From the σ–ε curves, the critical stress, σc, as well as the values of Young’s moduli of martensite and austenite are determined showing linear dependences on the temperature with a slope of 3.6 MPa/°C.

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“…Thermomagnetic measurements on Ni 55 Fe 20 Ga 25 alloys revealed evidence of two magnetic phases showing different Curie temperatures. [ 104 ] The lower T C (primary) phase was ascribed to the martensitic transition (MT) phase, and the higher T C phase (secondary) corresponded to the γ‐FCC of the alloy. The primary phase showed an order–disorder transition above RT (room temperature).…”

Section: Concerns With the Curie Transition Events In Ferromagnetic A...mentioning

confidence: 99%

Characterizing Curie and Néel Point Phase Transitions via Thermal Techniques

Reddy

Lakshya

Raj

et al. 2023

Physica Status Solidi (b)

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Various magnetic materials (for example, ferro, ferri, antiferromagnetic) are characterized by their respective transition temperatures (for example, Curie and Néel transitions). Knowledge of these transition temperatures is vital from an application standpoint. Accurate measurements by suitable characterization techniques are needed for identifying these transitions. Several techniques have been used to identify Curie and Néel transition temperatures, with thermal methods being one of the preferred choice. These thermal methods include differential scanning calorimetry (DSC), differential thermal analysis, and thermogravimetric analysis. Although thermal analysis tools have been popularly used for examining magnetic phase transitions, still much confusion exists on their efficacy and might. This review article highlights the strength and limitations of measuring Curie and Néel transitions by thermal techniques; measurements by DSC were the most common choice in previous works. Considering the intrinsic/fundamental nature of these Curie/Néel transitions, such confusion on their measurements (by thermal techniques) and their subsequent analysis (for the order of transition) suggests that a more comprehensive understanding of the events should be an immediate future goal for the research community, at large.

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Martensitic transformation and accompanying magnetic changes in Ni–Fe–Ga–Co alloys

Cited by 18 publications

References 21 publications

Effect of thermal treatments on the structural and magnetic transitions in melt-spun Ni-Fe-Ga-(Co) ribbons

Effect of thermal treatments on the structural and magnetic transitions in melt-spun Ni-Fe-Ga-(Co) ribbons

Temperature Dependent Stress–Strain Behavior and Martensite Stabilization in Magnetic Shape Memory Ni51.1Fe16.4Ga26.3Co6.2 Single Crystal

Characterizing Curie and Néel Point Phase Transitions via Thermal Techniques

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