High-temperature superelasticity in CoNiGa, CoNiAl, NiFeGa, and TiNi monocrystals

Chumlyakov, Yu. I.; Киреева, И. В.; Panchenko, E. Yu.; Timofeeva, Е. Е.; Pobedennaya, Z. V.; Chusov, S. V.; Караман, И.; Maier, Hans Jürgen; Cesari, E.; Кириллов, В.В.

doi:10.1007/s11182-009-9143-5

Cited by 54 publications

(51 citation statements)

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“…They are thought to be responsible for a high transformation temperature [7]. The same behavior was found in the crystals grown in our laboratory in which fcc cobalt solid solution nanoprecipitates [8] or hexagonal close packed (hcp) cobalt solid solution nanoprecipitates [9] were observed.…”

Section: Discussionsupporting

confidence: 75%

“…Previous studies on the Co 38 Ni 33 Al 29 alloy demonstrated strong dependence of its transformation properties on the thermomechanical history, mainly the crystallization velocity [5,6] and the same behavior was noticed on similar alloys as well [7]. Since it is known that the transformation can be aected by the complex distribution of the fcc cobalt solid solution particles within the B2 matrix in the bulk material, we performed neutron diraction experiments both on powder material and on quickly solidied bulk polycrystals with homogeneous distribution of the fcc particles.…”

Section: Introductionsupporting

confidence: 52%

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Martensitic Transformation in Co-Based Ferromagnetic Shape Memory Alloy

et al. 2012

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The Co38Ni33Al29 alloy in both powder and bulk state was investigated in the presented study using neutron diraction on E9 high resolution powder diractometer at HZB (BER II). The reverse martensitic phase transformation from the tetragonal martensitic phase into the cubic austenitic phase was observed with the phase coexistence within the temperatures from 183 K to 133 K. The fcc cobalt solid solution particles distributed in the transforming matrix remained in the same state through the whole temperature range. The obtained results agree with magnetization measurements on the same annealed sample. The powder data are compared with experiments on bulk sample, although there was a texture present. The obtained results provide further information about the phase transition process in this important class of ferromagnetic shape memory alloys.

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Section: Discussionsupporting

confidence: 75%

Section: Introductionsupporting

confidence: 52%

Martensitic Transformation in Co-Based Ferromagnetic Shape Memory Alloy

et al. 2012

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confidence: 99%

Thermoelastic γ–α′-martensitic transformations in FeNiCoAlTa aging single crystals

et al. 2011

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Thermoelastic martensitic transformations (MT) during cooling/heating and under loading give rise to functional properties such as the shape memory effect and superelasticity [1][2][3][4]. Fe -28% Ni -17% Co -11.5% Al -2.5% Ta -0.05% B (at.%) disordered iron-based alloys suggested by Y. Tanaka et al. in 2010 [5] have high strength, anomalously high superelasticity (of the order of 13%) caused by the γ-α′ MT under loading, good plasticity, and high damping ability in the polycrystalline state. High strength with anomalously high superelasticity of these alloys is reached due to precipitation of disperse γ′-phase particles [5]. Hardening of the γ-phase by disperse particles leads to the suppression of the plastic flow processes during the γ-α′ MT. The disperse γ′ particles undergo no MT, facilitate the accumulation of elastic energy in martensitic crystals, and change the degree of α′-martensite tetragonality; as a result, the volume change ΔV γ-α′ during MT is ≤1%. This is conventionally reached by precipitation of small disperse particles with sizes d < 10 nm [2,5].This work presents for the first time results of investigations into the development of thermoelastic γ-α′ MT in Fe -28% Ni -17% Co -11.5% Al -2.5 % Ta (at.%) single crystals. These investigations are necessary because of the following circumstances. First, single crystals give unique possibility to suppress the development of intermittent decomposition of polycrystals on grain boundaries caused by precipitation of the fragile intermetallic phase. Second, a comparison of data obtained for single and polycrystals of these alloys will allow the role of grains in the development of thermoelastic transformations to be elucidated.Single crystals of the Fe -28% Ni -17% Co -11.5% Al -2.5% Ta (at.%) alloy were grown from magnesium oxide in crucibles by the Bridgeman method in a helium atmosphere. They were aged at Т = 973 K for t = 0-25 h with subsequent water quenching. Temperatures of the γ-α′ MT were determined from bends of the curve showing the temperature dependence of the electrical resistance. Figure 1 shows the temperature dependence of the electrical resistance ρ(T) for crystals after quenching and aging at Т = 973 K. In the quenched state, no stages characteristic of the MT development are seen in the curve ρ(T) for these alloys, and ρ is independent of the temperature (curve 1 in Fig. 1) [2]. Aging at Т = 973 K for t = 7, 10, 15, and 20 h leads to the occurrence of stages in the curves ρ(T) (curves 2-5 in Fig. 1). According to [2], the temperature at which ρ(T) decreases corresponds to the temperature M s at which the MT is started during cooling, and the temperature at which the stage of fast decrease of the electrical resistance terminates corresponds to the temperature M f at which the direct MT is finished. During heating at temperature A s at which the inverse MT is started, the fast increase of ρ(T) is observed, and at Т = A f at which the inverse MT is finished, the fast increase of the electrical resistance is terminated. An analysis of cu...

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“…In Co 41 Ni 32 Al 27 single crystals, 3.3% magnetoinduced deformation is observed under the condition of simultaneous action of external stresses and magnetic field [1]. In quenched Co-Ni-Al single crystals oriented along [001] there is high-temperature superelasticity during tensile deformation up to the temperature 580 K with the value of reversible deformation being up to 7.0% [2][3][4]. The high-temperature phase of this alloy has a large region occupied by two phases and consists of their mixtur: В2-phase and γ-phase with an fcc-lattice not undergoing any MT but increasing plasticity of the brittle intermetallic compound [5].…”

Section: Introductionmentioning

confidence: 99%

Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

et al. 2011

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Using Co 35 Ni 35 Al 30 (at. %) single crystals, the effect of temperature and duration of aging on the development of thermoelastic B2-L1 0 -martensitic transformations during heating/cooling is studied. It is found out that at room temperature these single crystals are in the В2-phase and contain a small volume fraction (about 2%) of the plastic γ-phase. In the aged single crystals, in the В2-matrix, Co-rich particles with hcp-and fcc-lattices and metastable Ni 2 Al particles precipitate, whose size is determined by the temperature and duration of aging. It is shown that aging gives rise decreased temperature of martensitic transformations. At the aging temperatures T ≥ 673 K there is a sharp increase in the temperature hysteresis and a total suppression of thermoelastic B2-L1 0 -martensitic transformations during heating/cooling and under loading. A thermodynamic description of the starting temperature of martensitic transformations M s as a function of microstructure of the aged single crystals particle size and interparticle spacing is proposed.

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High-temperature superelasticity in CoNiGa, CoNiAl, NiFeGa, and TiNi monocrystals

Cited by 54 publications

References 32 publications

Martensitic Transformation in Co-Based Ferromagnetic Shape Memory Alloy

Martensitic Transformation in Co-Based Ferromagnetic Shape Memory Alloy

Thermoelastic γ–α′-martensitic transformations in FeNiCoAlTa aging single crystals

Characteristic features of development of thermoelastic transformations in aged single crystals of a CoNiAl ferromagnetic alloy

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