Kinetics of isothermal B2 → B19′ martensitic transformation in Ti49Ni51 shape memory alloy

Resnina, Natalia; Belyaev, Sergey; Demidova, Elena; Ivanov, Aleksei; Андреев, В. А.

doi:10.1016/j.matlet.2018.06.055

Cited by 13 publications

(10 citation statements)

References 11 publications

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“…Contrary to the forward transformation temperatures, a decrease in the cooling / heating rate decreases the reverse transformation temperatures if the stress is larger than 100 MPa. The observed phenomenon cannot be caused by the isothermal transformation, because the reverse transformation does not occur in the quenched Ni 51 Ti 49 alloy under isothermal conditions [10]. It is well known that the start temperature of the reverse thermoelastic transformation (A s ) is determined by the elastic energy that is stored during the forward transformation and the larger the energy the lower the A s temperature.…”

Section: Resultsmentioning

confidence: 99%

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

et al. 2019

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The influence of the cooling / heating rate on the martensitic transformation temperatures and the strain variation in the quenched Ni 51 Ti 49 alloy was studied. It was found that a decrease in the cooling / heating rate increased the temperatures of the forward transformation. It was assumed that this was due to the fact that the Ni 51 Ti 49 alloy was able to undergo the forward transformation on cooling, as well as during isothermal holding, which increased the transformation temperatures on slow cooling. The influence of the cooling / heating rate on the transformation temperatures depended on whether the stress affected the cooling and heating or not. It was shown that if the forward transformation occurred under a constant stress, then the influence of the cooling / heating rate on its temperatures became weak. However, the temperatures of the reverse transformation under load depended on the cooling / heating rate and this dependence was more significant for the start temperature of the reverse transformation A s than for the finish temperature. It was found that the cooling / heating rate did not affect the shape memory effect, however, this influenced the irreversible strain depending on the stress acting on cooling and heating. It was assumed that this might be caused by different mechanisms of the oriented martensite appearance.

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Section: Resultsmentioning

confidence: 99%

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

et al. 2019

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“…The martensite transformation, in turn, can lead to a strain variation. To take this mechanism into account, a new equation was included in the model to describe the rate of microplastic strain measures ε n mp : (7) where the dot indicates the time derivative of the corresponding variable, F n p and F n y are the generalized thermodynamic forces, the first of which causes the microplastic flow and the second describes the resistance associated with the non-oriented defects (scattered defects, which do not create oriented long-term stress field), and H is the Heaviside's function. The term r mp (T) corresponds to a relaxation process that controls the isothermal kinetics of the martensite transformation, and it is calculated according to formula:…”

Section: Theorymentioning

confidence: 99%

“…Recently, it has been shown that some NiTi-based shape memory alloys undergo the forward martensitic transformation during holding at a constant temperature close to M s (start temperature of the forward martensitic transition) [1][2][3][4][5][6][7]. The kinetics of this process is well studied experimentally, and it is established that the martensite volume fraction increases with time up to a saturation value, which depends on the holding temperature in a nonmonotonic way [5 -7].…”

Section: Introductionmentioning

confidence: 99%

Simulation of isothermal reversible strain in the Ti40.7Hf9.5Ni44.8Cu5 alloy using a microstructural model

Demidova

Belyaev

et al. 2021

Lett. Mater.

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Recently it has been found that some NiTi-based alloys may undergo the forward martensite transition on isothermal holding. Moreover, such isothermal transformation under stress is accompanied by variation in reversible strain. At the same time, theoretical models do not allow describing the recoverable strain variation during holding. The aim of the present study was to adjust the microstructural model earlier developed by V. Likhachev and A. Volkov for describing strain variation due to the formation of the martensite phase on holding of NiTi-based alloys under a constant stress at temperatures within the temperature range of the forward martensite transformation. To take into account the possibility for isothermal martensite formation, a new suggestion was made, according to which the isothermal kinetics might be controlled by some relaxation process, which could change the local density of point defects and led to the fulfillment of thermodynamics condition for transformation. To include this assumption into the model some modifications have been added to constitutive equations. The modified microstructural model was used to simulate the strain variation, caused by isothermal martensite formation under various stresses. The influence of holding parameters (temperature and stress) on the maximum isothermal strain was found, and a good agreement between the simulated and experimental results was obtained. It was shown that the modified microstructural model allowed predicting the holding temperature and the stress at which the maximum isothermal strain can be found.

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Section: Introductionmentioning

confidence: 96%

“…The realization of the forward B2 → B19' thermoelastic martensitic transformation under isothermal conditions was found in NiTi-based alloys with non-stoichiometric composition [1][2][3][4][5]. The volume fraction of the isothermal martensitic depended on the position of the holding temperature compared to the M s temperature and on the chemical composition of the alloy [4][5]. For example, during holding at the M s temperature, 45 % of martensite appeared isothermally in the quenched Ni 51 Ti 49 alloy and 80 % -in the Ti 40.7 Hf 9.5 Ni 44.8 Cu 5 alloy [4][5].…”

Section: Introductionmentioning

confidence: 97%

The strain variation during the isothermal B2→B19’ martensitic transformation in the quenched or annealed Ni₅₁Ti₄₉ alloy

Ivanov

Gabrielian

Belyaev

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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The strain variation during the isothermal holding under constant stress was studied in the quenched or annealed Ni51Ti49 alloy samples. The isothermal strain variation was found in both samples and this strain was completely recovered on subsequent unloading and heating. This allowed to conclude that the strain variation on holding was caused by the isothermal martensitic transformation. It was found that the maximum value of isothermal strain depended on the alloy heat treatment. This value was equal to 0.5 % in annealed sample and it was equal to 6 % in quenched sample. It was assumed that the formation of the Ni4Ti3 phase during annealing led to a decrease in concentration of substitutional Ni atoms in NiTi phase that were responsible for the isothermal transformation. As a result, the less volume fraction of the martensite formed during holding that supresses the strain variation in annealed samples.

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Kinetics of isothermal B2 → B19′ martensitic transformation in Ti49Ni51 shape memory alloy

Cited by 13 publications

References 11 publications

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

Simulation of isothermal reversible strain in the Ti40.7Hf9.5Ni44.8Cu5 alloy using a microstructural model

The strain variation during the isothermal B2→B19’ martensitic transformation in the quenched or annealed Ni₅₁Ti₄₉ alloy

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Kinetics of isothermal B2 → B19′ martensitic transformation in Ti49Ni51 shape memory alloy

Cited by 13 publications

References 11 publications

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

Influence of the cooling / heating rate on the martensitic transformation and functional properties of the quenched Ni51Ti49 shape memory alloy

Simulation of isothermal reversible strain in the Ti40.7Hf9.5Ni44.8Cu5 alloy using a microstructural model

The strain variation during the isothermal B2→B19’ martensitic transformation in the quenched or annealed Ni51Ti49 alloy

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Kinetics of isothermal B2 → B19′ martensitic transformation in Ti49Ni51 shape memory alloy

The strain variation during the isothermal B2→B19’ martensitic transformation in the quenched or annealed Ni₅₁Ti₄₉ alloy