共查询到20条相似文献,搜索用时 415 毫秒
1.
成功生长了Co50Ni21Ga29:Si(x=1,2)单晶样品,对其磁性,马氏体相变及其相关性质进行了细致的测量.发现掺Si成分的单晶具有非常迅速的马氏体相变行为、2.5%的大相变应变、大于100 ppm的磁感生应变和4.5%的相变电阻.进一步研究指出,在CoNiGa合金中掺入适量Si元素,能够降低材料的马氏体相变温度,减小相变热滞后,提高材料的居里温度,并使得磁性原子的磁矩有所降低.尤其重要的是Si元素的添加能够增大材料马氏体的磁晶各向异性能,改善马氏体变体的迁移特性,从而获得更大的磁感生应变.
关键词:
铁磁形状记忆合金
Heusler合金
50Ni21Ga29Six')" href="#">Co50Ni21Ga29Six 相似文献
2.
The effect of Si content on the martensitic transfor-mation temperature of Ni55.5e18Ga26.5-xSix alloys 下载免费PDF全文
This paper investigates the effects of substitution of Si for Ga on the martensitic transformation behaviours in Ni-Fe-Ga alloys by using optical metallographic microscope and differential scanning calorimetry (DSC) methods. The structure type of Ni55.5Fe18Ga26.5-xSix alloys is determined by x-ray diffraction (XRD), and the XRD patterns show the microstructure of Ni-Fe-Ga-Si alloys transformed from body-centred tetragonal martensite (with Si content x = 0) to body-centred cubic austenite (with x = 2) at room temperature. The martensitic transformation temperatures of the Ni55.5Fe18Ga26.5-xSix alloys decrease almost linearly with increasing Si content in the Si content range of x ≤ 3. Thermal treatment also plays an important role on martensitic transformation temperatures in the Ni-Fe-Ga-Si alloy. The valence electronic concentrations, size factor, L21 degree of order and strength of parent phase influence the martensitic transformation temperatures of the Ni-Fe-Ga-Si alloys. An understanding of the relationship between martensitic transformation temperatures and Si content will be significant for designing an appropriate Ni-Fe-Ga-Si alloy for a specific application at a given temperature. 相似文献
3.
A.K. Panda Satnam SinghR.K. Roy M. GhoshA. Mitra 《Journal of magnetism and magnetic materials》2011,323(9):1161-1169
The investigation addresses the effect of Mn incorporation for Ni on the properties of a series of Ni77−xMnxGa23 (x=22-29; at%) ferromagnetic shape memory alloys prepared in the form of ribbons by a melt spinning technique. Phase transformation studies in these ribbons by differential scanning calorimetry revealed that austenitic start and martensitic start temperatures decreased with the increase in Mn content. The Curie temperature (TC) of these alloys determined from thermal variation of magnetisations was found to rise with increasing Mn content. The martensitic transformation temperatures were above TC in low Mn containing (x=22 and 23) alloys. Morphology observed through transmission electron microscopy manifested complex martensitic features in the alloy with x=22 while x=29 had an austenitic phase. The alloys with intermediate Mn content (x=24, 25) had overlapping magnetic and martensitic transformations close to room temperature. The thermal lag between austenitic and martensitic characteristic temperatures in these alloys has been corroborated to their structural state. X-ray diffraction indicated a predominant martensite phase and austenite phase in low and high Mn containing alloys respectively. In-situ diffraction studies during thermal cycle indicate martensite-austenite transformations. 相似文献
4.
Yu. V. Kaletina E. G. Gerasimov V. A. Kazantsev A. Yu. Kaletin 《Physics of the Solid State》2017,59(10):2002-2007
Thermal expansion and structural and magnetic phase transitions in alloys of the Ni–Mn–Sn system have been investigated. The spontaneous martensitic transformation in Ni51–xMn36 + xSn13 (0 ≤ x ≤ 3) alloys is found to be accompanied by high jumps in the temperature dependences of the linear thermal expansion. The relative change in the linear sizes of these alloys at the martensitic transformation is ~1.5 × 10–3. There are no anomalies in the magnetic-ordering temperature range in the temperature dependences of the coefficient of linear thermal expansion. The differences in the behavior of linear thermal expansion at the martensitic transformation in Ni51–xMn36 + xSn13 (0 ≤ x ≤ 3) and Ni47Mn40Sn13(x = 4) alloys have been established. 相似文献
5.
6.
The martensitic phase transformation has no observable effect on the magnetic susceptibility of Ce in LaAg
x
In1–x
which agrees with the assumption of a crystal field splitting by 300 K of the2
F
5/2 ground state of Ce3+ ions. The magnetic ordering temperature and the Kondo minimum move to higher temperatures together with the martensitic phase transformation when the Ag concentration is reduced. This behavior can be related qualitatively to the lowering of the 5d – e
g levels in the center of the Brillouin-zone with increasing In content. 相似文献
7.
The martensitic phase transformation has no observable effect on the magnetic susceptibility of Ce in LaAg
x
In1–x
which agrees with the assumption of a crystal field splitting by 300 K of the2
F
5/2 ground state of Ce3+ ions. The magnetic ordering temperature and the Kondo minimum move to higher temperatures together with the martensitic phase transformation when the Ag concentration is reduced. This behavior can be related qualitatively to the lowering of the 5d – e
g levels in the center of the Brillouin-zone with increasing In content. 相似文献
8.
The effects of Sn addition on phase transformation behavior and magnetocaloric properties of Mn50Ni25Ga25−xSnx (x=0, 0.1, 0.5, 1 and 2 at%) alloys were investigated in this work. The results show that the addition of Sn reduces the structural transformation temperatures. It is found that the second phase exists in the austenite matrix of the as-casted alloys at room temperature. After being annealed at 1073 K for 48 h, the precipitates totally soluted into the matrix. Magnetization measurements indicate that the saturation magnetizations of the alloys increase significantly with increase in Sn contents. In addition, the ΔM/ΔS obviously increases with increase in the Sn contents, implying the higher efficiency shift of the martensitic transformation temperature under the magnetic field. 相似文献
9.
通过结构以及磁性测量,研究了哈斯勒合金Ni50Mn25+xSn25-x (x=11,12)的马氏体相变和磁热性质.结果表明,与样品在奥氏体相的磁性不同,由于在马氏体相中反铁磁交换作用的增强,导致铁磁和反铁磁在马氏体状态下共存.此外,通过Maxwell方程,研究了两样品在不同磁场变化下马氏体相变温度附近的反磁热性质,并阐明了该系列合金产生大的正磁熵变(ΔSM)不仅与其在降温过程中发生马氏体相变所导致的磁跃变(ΔM)有关,而且与发生马氏体相变所经历的温度区间有密切的联系.
关键词:
哈斯勒合金
Ni-Mn-Sn
马氏体相变
正磁熵变 相似文献
10.
V. G. Pushin N. I. Kourov A. V. Korolev V. V. Marchenkov E. B. Marchenkova V. A. Kazantsev N. N. Kuranova A. G. Popov 《Physics of the Solid State》2013,55(12):2413-2421
The magnetic and thermoelastic martensitic transformations and physical properties (magnetization, electrical resistivity, thermoelectric power, relative elongation, and thermal expansion coefficient) of multicomponent magnetic shape memory alloys Ni50 ? x Co x Mn29Ga21 (x = 0, 1, 2, 3, 10 at %) have been investigated. The critical temperatures of thermoelastic martensitic transformation and magnetic transitions have been determined. It has been found that the alloy with 10 at % Co undergoes a martensitic transformation in the temperature range of 6–10 K. 相似文献
11.
Jie ChenZhida Han Bin Qian Ping ZhangDunhui Wang Youwei Du 《Journal of magnetism and magnetic materials》2011,323(2):248-251
The effects of Al substitution on the phase transitions and magnetocaloric effect of Ni43Mn46Sn11−xAlx (x=0-2) ferromagnetic shape memory alloys were investigated by X-ray diffraction and magnetization measurements. With the increase of Al content, the cell volume decreases due to the smaller radius of Al, and the martensitic transformation temperature increases rapidly, while the Curie temperature of austenitic phase shows a small increase. A large positive and a negative magnetic entropy change were observed near the first-order martensitic transition and the second-order magnetic transition, respectively. The magnetic entropy changes, hysteresis behavior, and refrigerant capacity near the two transitions are compared. 相似文献
12.
Combined experimental and theoretical study on the effect of Nb content on martensitic transformation of NbRu shape memory alloys 下载免费PDF全文
The effect of Nb content on the martensitic transformation
of NbRu high-temperature shape memory alloys is investigated by
experiments and first-principles calculations. We calculate the
lattice parameters, density of states, charge density, and heats of
formation of Nb50+xRu50-x β phase. The
results show that an increase in Nb content increases the stability
of Nb50+xRu50-x β phase, leading to a
significant decrease of the β to β' martensitic
transformation temperature. In addition, the mechanism of the
effects of Nb content on phase stability and martensitic
transformation temperature is studied on the basis of
electronic structure. 相似文献
13.
A. B. Granovskii V. N. Prudnikov A. P. Kazakov A. P. Zhukov I. S. Dubenko 《Journal of Experimental and Theoretical Physics》2012,115(5):805-814
The magnetization, the electrical resistivity, the magnetoresistance, and the Hall resistivity of Ni50Mn35In15 ? x Si x (x = 1.0, 3.0, 4.0) Heusler alloys are studied at T = 80-320 K. The martensitic transformation in these alloys occurs at T = 220?C280 K from the high-temperature ferromagnetic austenite phase into the low-temperature martensite phase having a substantially lower magnetization. A method is proposed to determine the normal and anomalous Hall effect coefficients in the presence of magnetoresistance and a possible magnetization dependence of these coefficients. The resistivity of the alloys increases jumpwise during the martensitic transformation, reaches 150?C200 ??? cm, and is almost temperature-independent. The normal Hall effect coefficient is negative, is higher than that of nickel by an order of magnitude at T = 80 K, decreases monotonically with increasing temperature, approaches zero in austenite, and does not undergo sharp changes in the vicinity of the martensitic transformation. At x = 3, a normal Hall effect nonlinear in magnetization is detected in the immediate vicinity of the martensitic transformation. The temperature dependences of the anomalous Hall effect coefficient in both martensite and austenite and, especially, in the vicinity of the martensitic transformation cannot be described in terms of the skew scattering, the side jump, and the Karplus-Lutinger mechanisms from the anomalous Hall effect theory. The possible causes of this behavior of the magnetotransport properties in Heusler alloys are discussed. 相似文献
14.
K. A. Yurchenko L. I. Yurchenko N. I. Kourov V. G. Pushin 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(10):1442-1444
The crystal structure of NiMn alloy alloyed by titanium in a wide range of temperatures and compositions has been investigated using resistivity measurements, transmission electron microscopy, electron diffraction, and X ray diffraction. It is found that alloying by titanium not only decreases the martensitic transformation temperature but also changes the martensite crystal structure. The martensitic transformation temperatures are determined and the diagram of martensitic transformations for Ni50Mn50 ? x Ti x alloys is constructed. 相似文献
15.
The martensitic transformation was investigated in a set of twin roller melt-spun Cu–Zn–Al shape memory alloys, solidified at tangential wheel speeds between 20 and 40 m/s. The resulting microstructures were analyzed using X-ray diffraction, optical and transmission electron microscopy techniques. The characteristic martensitic transformation temperature, M S, was determined for each condition by conventional resistometric methods. The ribbons are homogeneous in shape and for each quenching rate they exhibit a quite uniform M S temperature. By proper thermal treatments, the different factors affecting M S could be separately examined and from temperature measurements, the contribution of L21 antiphase boundaries evaluated. A calculation of this contribution using pair interchange energies is in good agreement with the experimental results. 相似文献
16.
B. Gao J. Shen F. X. Hu J. Wang J. R. Sun B. G. Shen 《Applied Physics A: Materials Science & Processing》2009,97(2):443-447
The influence of Cu substitution for Mn on magnetic properties and magnetic entropy change has been investigated in Heusler
alloys, Ni50Mn35−x
Cu
x
Sn15 (x=2,5 and 10). With increasing Cu content from x=2 to x=5, the martensitic transition temperature, T
M
, decreases from 220 K to 120 K. Further increasing Cu up to x=10 results in the disappearance of T
M
. For samples Ni50Mn33Cu2Sn15 and Ni50Mn30Cu5Sn15, both martensitic and austenitic states exhibit ferromagnetic characteristics, but the magnetization of martensitic phase
is notably lower than that of austenitic phase. The magnetization difference, ΔM, across the martensitic transition leads to a considerably large Zeeman energy, μ
0ΔM⋅H, which drives a field-induced metamagnetic transition. Associated with the metamagnetic behavior, a large positive magnetic
entropy change ΔS takes place around T
M
. For the sample Ni50Mn33Cu2Sn15,ΔS reaches 13.5 J/kg⋅K under a magnetic field change from 0 to 5 T. 相似文献
17.
Diffuse scatterings appearing in electron diffraction patterns of Ti–(50???x)Ni–xFe (x?=?6, 7, 8, 10, in at.%) alloys were investigated. In the alloys, martensitic (R-phase) transformation is suppressed down to 4.2 K, but the electrical resistivity exhibits a local minimum at T min (210 K, 195 K, 180 K and 140 K for x?=?6, 7, 8, 10, respectively). The following results were obtained for all the alloys. Diffuse scattering appears below T min and its intensity maximum is located at an incommensurate position of g?+??ζζ0?*, where g is a reciprocal lattice vector of the B2-phase. The value?ζ?at T min is significantly smaller than 1/3 and increases with decreasing temperature; it decreases with increasing Fe content. The value of?ζ?at T min agrees with the length of nesting vector obtained by a band calculation, suggesting that the diffuse scattering is caused by the nesting effect of the Fermi surface in the B2-type structure. 相似文献
18.
Effects of pre-deformation on the martensitic transformation and magnetocaloric property in Ni-Mn-Co-Sn ribbons 下载免费PDF全文
This paper investigates the martensitic transformation and magnetocaloric effect in pre-deformed Ni-Mn-Co-Sn ribbons.The experimental results show that the reverse martensitic transformation temperature T M increases with the increasing pre-pressure,suggesting that pre-deformation is another effective way to adjust T M in ferromagnetic shape memory alloys.Large magnetic entropy changes and refrigerant capacities are obtained in these ribbons as well.It also discusses the origin of the enhanced martensitic transformation temperature and magnetocaloric property in pre-deformed Ni-Mn-Co-Sn ribbons. 相似文献
19.
Ni–Mn-based metamagnetic shape memory alloys have been proposed as potential elastocaloric refrigerants. The intrinsic brittleness of the alloys has limited their cooling application. Introducing a soft second phase is an effective way to reduce the brittleness. From the viewpoint of application, the effect of second phase on elastocaloric effect should be illustrated. In this paper, we have investigated the microstructure, martensitic transformation and elastocaloric effect of Ni45Mn37-xIn13Co5Crx () polycrystalline alloys. Single-phase and precipitates-containing microstructures are obtained for the undoped and doped alloys, respectively. The precipitates in Cr-doped alloys enhances the fracture strength but significantly hinders the martensitic transformation. Balancing the fracture strength and martensitic transformation, the Ni45Mn36In13Co5Cr alloy with small amount of precipitates along grain boundaries exhibits large cooling effects of 4–6 K in the temperature range of 317–353 K. 相似文献
20.
Martensitic transformations and magnetic properties of Ni89-x Mn x In11 (42 ≤ x ≤ 44) alloys have been investigated. Critical temperatures of magnetic and structural phase transitions in the studied alloy system have been determined. It has been shown that the martensitic transformation induced by the magnetic field is observed in all alloys. Temperature dependences of the spontaneous magnetization of austenite and martensite as well as the magnitude of the critical field, in which martensitic transformation occurs, have been determined. 相似文献