Martensitic transformation in Co2NiGa ferromagnetic shape memory alloys

Crăciunescu, Corneliu Marius; Kishi, Yoji; Lograsso, Thomas A.; Wuttig, Manfred

doi:10.1016/s1359-6462(02)00148-3

Cited by 81 publications

(43 citation statements)

References 15 publications

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“…The extrapolation of the stability regions of bcc-type B2 phases of the binary Co-Ga and Ni-Ga alloys suggests that ternary compositions with a bcc lattice structure, which may transform martensitically, might exist in the vicinity of the stoichiometric composition. 36 Experimental characterization reveals, however, that in order to obtain pure ␤ ͑bcc͒ phases a Ga content of at least 30% is required, while at the stoichiometric composition a rather mixture of segregated ␤ and ␥ ͑fcc͒ phases is found. This narrows the range of martensitically transforming compositions since with increasing Ga content ͑and thus decreasing e / a͒, the martensitic transformation temperatures decrease.…”

Section: A Martensitic Transformations and Binding Surface In Stoichmentioning

confidence: 99%

“…A similar behavior is obtained if Ni is replaced by Co. As a limit for nonvanishing martensite transition temperatures e / a Ϸ 7.3 has been proposed in the past. 36 On the other hand, the Curie temperatures show the opposite trend with increasing Co content, which means that a sufficient amount of Co is necessary to stabilize the ferromagnetism at appropriate operating temperatures. This dramatically narrows the range of compositions in which alloys with suitable MSM properties can be found.…”

Section: A Martensitic Transformations and Binding Surface In Stoichmentioning

confidence: 99%

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Electronic structure and lattice dynamics of the magnetic shape-memory alloyCo2NiGa

et al. 2010

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In addition to the prototypical Ni-Mn-based Heusler alloys, the Co-Ni-Ga systems have recently been suggested as another prospective materials class for magnetic shape-memory applications. We provide a characterization of the dynamical properties of this material and their relation to the electronic structure within a combined experimental and theoretical approach. This relies on inelastic neutron scattering to obtain the phonon dispersion while first-principles calculations provide the link between dynamical properties and electronic structure. In contrast to Ni 2 MnGa, where the softening of the TA 2 phonon branch is related to Fermi-surface nesting, our results reveal that the respective anomalies are absent in Co-Ni-Ga, in the phonon dispersions as well as in the electronic structure. Keywords Materials Science and Engineering Disciplines Condensed Matter Physics | Materials Science and Engineering CommentsThis article is from Physical Review B 82 (2010) In addition to the prototypical Ni-Mn-based Heusler alloys, the Co-Ni-Ga systems have recently been suggested as another prospective materials class for magnetic shape-memory applications. We provide a characterization of the dynamical properties of this material and their relation to the electronic structure within a combined experimental and theoretical approach. This relies on inelastic neutron scattering to obtain the phonon dispersion while first-principles calculations provide the link between dynamical properties and electronic structure. In contrast to Ni 2 MnGa, where the softening of the TA 2 phonon branch is related to Fermisurface nesting, our results reveal that the respective anomalies are absent in Co-Ni-Ga, in the phonon dispersions as well as in the electronic structure.

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Section: A Martensitic Transformations and Binding Surface In Stoichmentioning

confidence: 99%

Section: A Martensitic Transformations and Binding Surface In Stoichmentioning

confidence: 99%

Electronic structure and lattice dynamics of the magnetic shape-memory alloyCo2NiGa

et al. 2010

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“…Each ingot was melted five times to ensure homogeneity; and finally the melted alloy was suck-cast into a water-cooled cylindrical copper mold placed at the bottom of the arc furnace to form an alloy rod with a constant diameter of 3 mm. The alloys contained 0, 2, 4, 6 or 8 at% of Co, in terms of the baseline Ni 52.5 Mn 23.5 Ga 24 , and have been designated NMG-C0, NMG-C2, NMG-C4, NMG-C6 and NMG-C8, respectively. The alloy rods were annealed in evacuated quartz tubes at 1000°C for 24 h for further homogenization.…”

Section: Methodsmentioning

confidence: 99%

“…The number of valence electrons is assumed to be 10 for Ni, 7 for Mn, 3 for Ga and 9 for Co. The addition of Co to the baseline alloy Ni 52.5 Mn 23.5 Ga 24 increases the e/a ratio, and, in turn, increases the phase transformation temperatures, as also shown in Figure 2. The thermal hysteresis of the phase transformation, the difference between A f and M s , is increased as the Co content increases.…”

Section: Phase Transformation Temperaturesmentioning

confidence: 99%

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Effect of Co on the martensitic transformation, crystal structure and magnetization of Ni52.5Mn23.5Ga24 based ferromagnetic shape memory alloys

Yan

Chi

et al. 2011

Chin. Sci. Bull.

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Five (Ni 52.5 Mn 23.5 Ga 24 ) 100-x Co x (x = 0, 2, 4, 6, 8) alloys were prepared by arc melting, and the effects of Co addition on the martensitic phase transformation, crystal structure and magnetization were investigated. The phase transformation temperatures M s , M f , A s and A f are proportional to the content of Co in the (Ni 52.5 Mn 23.5 Ga 24 ) 100-x Co x alloys, which appears to be due to the variation in the valance electron concentration. The Curie temperature is sensitive to the composition of the alloy. As the amount of Co changes, both the Co-Mn exchange interaction and the distance between Mn atoms change. These, in turn, affect the Curie temperature and magnetization behavior of the alloy. The martensite phases in all the alloys are domained in three different orientations, the domain boundary was determined to belong to the family of {1 1 2} lattice planes. a magnetic field than thermally controlled shape memory alloys [5,6], which makes them highly interesting for many novel technological applications especially as actuators [7,8]. The induced strain from the magnetic field forces a rearrangement of the crystallographic orientation of the martensitic variants formed during the thermoelastic martensitic transformation [9]. The martensitic transformation start temperature, M s , of a Ni 2 MnGa based alloy is strongly depended on its composition; the Curie temperature (T C ) is, however, less sensitive [10]. The temperature range for producing the magnetic field induced strain, which can be up to 10% of the value, is determined by the M s and T C and can be optimized for specific applications by changes in the alloy composition. Ni-Mn-Ga alloy, Martensitic transformation, domain boundary, Curie temperature, magnetizationOther than the elements Fe [11][12][13] [18] and others, which have been confirmed to affect the characteristics of these Ni-Mn-Ga Heusler alloys, the ferromagnetic 3d transition element Co has been frequently used to modify phase transformation temperatures,

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On the Impact of Additive Manufacturing Processes on the Microstructure and Magnetic Properties of Co–Ni–Ga Shape Memory Heusler Alloys

et al. 2022

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Ferromagnetic shape memory alloys (FMSMAs) show a large magnetic fieldinduced strain up to 10%, [1,2] which makes this materials interesting for magnetic actuators. [3] A promising material class for FMSMAs are Heusler alloys, such as Ni-Mn-X (X: Ga, In, Sn, Al), [2,[4][5][6][7][8] Ni-Fe-Ga, [9] or Co-Ni-X (X: Al, Ga), [10][11][12] exhibiting a large shape memory effect owing to a reversible martensitic transformation. The investigated Co-Ni-Ga Heusler alloy undergoes a first-order magnetostructural transformation (FOMST) from hightemperature B2-ordered austenite to lowtemperature tetragonal L1 0 martensite. [13] A fully reversible superelastic response as well as excellent cyclic stability up to temperatures of 373 K has been reported for single crystals. [12] However, polycrystalline Co-Ni-Ga as well as other polycrystalline Heusler alloys suffer from intergranular cracking and premature failure after several transformation cycles due to the anisotropic volume change of randomly orientated grains. [14,15]

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Martensitic transformation in Co2NiGa ferromagnetic shape memory alloys

Cited by 81 publications

References 15 publications

Electronic structure and lattice dynamics of the magnetic shape-memory alloyCo2NiGa

Electronic structure and lattice dynamics of the magnetic shape-memory alloyCo2NiGa

Effect of Co on the martensitic transformation, crystal structure and magnetization of Ni52.5Mn23.5Ga24 based ferromagnetic shape memory alloys

On the Impact of Additive Manufacturing Processes on the Microstructure and Magnetic Properties of Co–Ni–Ga Shape Memory Heusler Alloys

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