Microstructure and martensitic transformation characteristics of CoNiGa high temperature shape memory alloys

Dogan, E.; Караман, И.; Chumlyakov, Y.I.; Luo, Zhiping

doi:10.1016/j.actamat.2010.10.050

Cited by 64 publications

(29 citation statements)

References 44 publications

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“…Compared with metallic shape memory alloys (SMAs), shape memory ceramics offer many advantages such as high operating temperature, high strength and chemical inertness [2][3][4][5]. The first suggestion of the shape memory effect in ceramics can be traced to 1986 when Swain et al reported that a 9.4% MgO stabilized tetragonal zirconia polycrystal (Mg-TZP) ceramic was able to recover a strain of about 0.5% after being heated to 800°C [6].…”

mentioning

confidence: 99%

Size effects and shape memory properties in ZrO2 ceramic micro- and nano-pillars

Zeng

Qing

et al. 2015

Scripta Materialia

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mentioning

confidence: 99%

Size effects and shape memory properties in ZrO2 ceramic micro- and nano-pillars

Zeng

Qing

et al. 2015

Scripta Materialia

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“…Since Ullakko et al [21] discovered large magnetic field-induced strains (MFISs) in Heusler alloy Ni 2 MnGa single crystal in 1996, many Heusler alloys have been investigated extensively such as NiMnZ (Z = In, Sn, Sb, Al) [22][23][24], NiCoMnZ (Z = In, Sn, Sb, Al, Ga) [6,25,26], Ni 2 FeZ [27][28][29][30][31], Mn 2 NiZ [32,33], Fe 2 MnZ [34,35], and Co 2 NiZ [36][37][38]. This kind of MFISs exhibit many merits, such as large strain, high work output, high response frequency, and tunable working temperature.…”

Section: Introductionmentioning

confidence: 99%

Recent progress in Heusler-type magnetic shape memory alloys

Liu

et al. 2015

Rare Met.

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Magnetic shape memory alloys (MSMAs), both in condensed matter physics and in material science, are one of the most extensive research subjects. They show prompt response to the external magnetic field and give rise to large strain and have fine reversibility. The well-known example is Heusler-type MSMAs, which possess excellent multifunctional properties and have potential applications in energy transducer, actuator, sensor, microelectromechanical system, and magnetic refrigerator. In this paper, it is shown the recent progress in magnetostructural transformation, magnetic properties, shape deformation, magnetocaloric effect as well as magnetic field-induced shape memory effect in Ni-Mn-Ga, NiMnZ (Z = In, Sn, Sb), and NiCoMnZ (Z = In, Sn, Sb, Al) Heusler-type MSMAs. The remaining issues and possible challenges are briefly discussed.

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“…Additionally, it shows martenstic start (M s ) temperatures up to 250°C 3 . The CoNiGa alloy with a stoichiometric Heusler type composition (Co 2 NiGa) is a primary candidate for applications requiring ferromagnetic shape memory alloys [4][5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

Stability analysis of the martensitic phase transformation inCo2NiGaHeusler alloy

et al. 2015

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Phase competition and the subsequent phase selection are important characteristics of alloy systems exhibiting numerous states of distinct symmetry but comparable energy. The stoichiometric Co 2 NiGa Heusler alloy exhibits a martensitic transformation with concommitant reduction in symmetry from a austentic L2 1 phase (cubic) to a martensitic L1 0 phase (tetragonal). A structural search was carried out for this alloy and it showed the existence of a number of structures with monoclinic and orthorhombic symmetry with ground state energies comparable to and even less than that of the L1 0 structure, usually reported as the ground state at low temperatures. We describe these structures and focus in particular on the structural transition path from the L2 1 to tetragonal and orthorhombic structures for this material. Calculations were carried out to study the Bain (L2 1 − L1 0 ) and Burgers (L2 1 − hcp) transformations. The barrierless Burgers path yielded a stable martensitic phase with orthorhombic symmetry (O) with energy much lower-beyond the expected uncertainty of the calculation methods-than the known tetragonal L1 0 martensitic structure. This low energy structure (O) has yet to be observed experimentally and it is thus of scientific interest to discern the cause for the apparent discrepancy between experiments and calculations. It is postulated the the Co 2 NiGa Heusler system exhibits a classic case of the phase selection problem: although the unexpected O phase may be relatively more stable than the L1 0 phase, the energy barrier for the (L2 1 − O) transformation may be much higher than the barrier to the (L2 1 − L1 0 ) transformation. To validate this hypothesis, the stability of this structure was investigated by considering the contributions of elastic, vibrational effects, configurational disorder, magnetic disorder and atomic disorder. The calculations simulating the effect of magnetic disorder/ high temperature as well as the atomic disorder simulations showed that the transformation from L2 1 to L1 0 is favored over the Burgers path at high temperatures (large magnetic disorder). These conditions are prevalent upon cooling the material from high temperatures (the usual synthesis route), and this provides a plausible explanation why L1 0 and not the O phase is observed. Other ground states (not observed in experiments but predicted through calculations) are ruled out in terms of symmetry relations as well as through considerations of elastic barriers to their nucleation.

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Microstructure and martensitic transformation characteristics of CoNiGa high temperature shape memory alloys

Cited by 64 publications

References 44 publications

Size effects and shape memory properties in ZrO2 ceramic micro- and nano-pillars

Size effects and shape memory properties in ZrO2 ceramic micro- and nano-pillars

Recent progress in Heusler-type magnetic shape memory alloys

Stability analysis of the martensitic phase transformation inCo2NiGaHeusler alloy

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