Changes in the electronic structure upon the B2–B19′ martensitic transformation in titanium-nickel

Kulkova, S. E.; Valujsky, D.V.; Smolin, I. Yu.

doi:10.1134/1.1366004

Cited by 8 publications

(9 citation statements)

References 17 publications

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“…According to Eq. (1), during this TMT, the density of electronic states at the Fermi level n(E F ) must be changed by almost the same value, which agrees with some energy band calculations (e.g., [8,9] and Refs. in them).…”

Section: Magnetic Susceptibilitysupporting

confidence: 88%

“…This agrees with the calculations of the electronic band structure of Ti-Ni alloys (e.g., [8][9][10]). However, the behavior of the electronic properties during TMTs such as B2 ↔ R and R ↔ B19' is less unambiguous.…”

Section: Introductionsupporting

confidence: 90%

“…(2) made it possible to conclude that the Fermi level in the Ti 50 Ni 50x Cu x alloys was at the left slope of the high-energy peak in the curve of density of states n(E). According to the energy band calculations (e.g., [8,9]) this n(E) peak that determines the stability of the B2 structure in Ti-Nibased alloys is mainly due to the titanium 3d states. The increase in the value of S d in going from the austenitic B2 to the martensitic B19' phase (curve 1 in Fig.…”

Section: Thermoelectric Powermentioning

confidence: 99%

“…According to the energy band calculations [8,9], the shift of the Ti-Ni alloy composition to higher concentrations of titanium atoms must increase the density of the electronic states at the Fermi level n(E F ). In turn, the increase in n(E F ) must be accompanied with the increase in the structural instability of the B2 austenite of the alloy.…”

Section: Alloys Near the Stoichiometric Ti-ni Compositionmentioning

confidence: 99%

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Specific features of the electronic properties of Ti50Ni50–x Cu x alloys with the shape memory effect

et al. 2016

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Section: Magnetic Susceptibilitysupporting

confidence: 88%

Section: Introductionsupporting

confidence: 90%

Section: Thermoelectric Powermentioning

confidence: 99%

Section: Alloys Near the Stoichiometric Ti-ni Compositionmentioning

confidence: 99%

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Specific features of the electronic properties of Ti50Ni50–x Cu x alloys with the shape memory effect

et al. 2016

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“…These values of the coefficients γ and β agree satisfactorily with the values obtained in [3]. Hence, we can calcu late the density of electron states at the Fermi level n(E F ) = 0.85 state/eV atom and the Debye tempera ture θ D = 309 K. The electron energy band calcula tions performed in [4] give a quite wide spectrum of values of n(E F ) for the NiTi alloy of equiatomic com position in the low temperature B19' phase. We found the value of n(E F ) for the initial microcrystalline Ni 50.5 Ti 49.5 alloy having the martensite B19' structure at low temperatures, which is in the closest agreement with the results obtained in [5][6][7].…”

supporting

confidence: 63%

Effect of plastic deformation by torsion on the heat capacity of the Ni50.5Ti49.5 alloy

2012

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883Studies of titanium nickelide based shape memory alloys (see, e.g., [1] and references therein) show that severe plastic deformation by torsion under high pres sure (HPT) in Bridgman anvils causes the transition of the microcrystalline structure of initial samples to the amorphous-nanocrystalline state. In this case, the electronic and lattice properties of the alloys are changed substantially. As a result of HPT, the electrical resistivity increases several times, and the dependence ρ(T) has a negative slope below room temperature. The studies of the magnetic susceptibility and optical properties of the alloys show that HPT decreases the density of states at the Fermi level n(E F ). However, the changes in the thermopower S and the Hall coefficient R 0 observed in the Mott two band model do not agree with the results of the magnetic and optical studies. The behavior of the physical properties of the alloys subjected to plastic deformation testifies that the plas tic deformation suppresses the martensitic transfor mation with which the shape memory effect is com monly associated.The aim of this work is to study the change in the heat capacity C P (T) of the shape memory alloy Ni 50.5 Ti 49.5 as a result of its atomic and structural disor dering by torsion under a pressure of 6 GPa through five revolutions of Bridgman anvils at room tempera ture. The heat capacity C P (T) was measured during cooling the samples from 310 to 2 K on a Quantum Design PPMS 9 device (USA) at the Department of Magnetic Measurements of the Institute of Metal Physics, Ural Branch of the Russian Academy of Sci ences (Yekaterinburg). The initial samples were pre pared from the components 99.99% pure by the elec tric arc melting in a helium atmosphere. According to the data of chemical analysis, the elemental composi tion of impurities in the alloy was as follows (wt %): C = 0.0372, S = 0.0001, O 2 = 0.0167, N = 0.0003. The technique of preparing the alloys was described in more detail in [1,2]. The effect of plastic deformation on the thermal expansion and the kinetic, magnetic, and optical properties of the alloy were studied in [1].The results of measurements of C p (T) of the initial (microcrystalline, with the mean grain size of 40 μm) and plastically deformed (amorphous-nanocrystal line) Ni 50.5 Ti 49.5 alloys are shown in Figs. 1 and 2. It is seen from the data presented in Fig. 1a, that, in the limit of the lowest temperatures (2 K ≤ T ≤ 30 K), the heat capacity of the initial alloy is described by the standard relationship (1) Here, the coefficient γ = = 2 mJ/g atom K 2 characterizes the electronic component, and β = = 6.58 × 10 -5 mJ/g atom K 4 character izes the lattice (Debye) component; k B is the Boltz mann constant; and N A is the Avogadro number. These values of the coefficients γ and β agree satisfactorily with the values obtained in [3]. Hence, we can calcu late the density of electron states at the Fermi level n(E F ) = 0.85 state/eV atom and the Debye tempera ture θ D = 309 K. The electron energy band calcula tions perf...

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Electronic structure of low-index surfaces in austenitic and martensitic phases of TiNi and TiPd alloys

Kulkova

Егорушкин

Eremeev

et al. 2004

Physica B: Condensed Matter

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Changes in the electronic structure upon the B2–B19′ martensitic transformation in titanium-nickel

Cited by 8 publications

References 17 publications

Specific features of the electronic properties of Ti50Ni50–x Cu x alloys with the shape memory effect

Specific features of the electronic properties of Ti50Ni50–x Cu x alloys with the shape memory effect

Effect of plastic deformation by torsion on the heat capacity of the Ni50.5Ti49.5 alloy

Electronic structure of low-index surfaces in austenitic and martensitic phases of TiNi and TiPd alloys

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