共查询到20条相似文献,搜索用时 15 毫秒
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利用X射线衍射研究了CoNiZ(Z=Si,Sb,Sn,Ga等)合金在不同热处理条件下的相组成.当Z元素为Sn,Sb时,材料是完全的B2结构;但Z为Si时,材料变成面心立方的γ相.形成B2还是γ相由电子浓度和原子尺寸效应两种因素共同决定.而CoNiGa的研究结果表明,在合金中除了形成B2结构的同时还容易形成γ相,常表现出两相共存的特性.对材料进行不同方式的热处理可以使合金中两相的含量有所消长,γ相含量的多少对CoNiGa合金的马氏体相变有很大的影响.分析指出,两相共存及其所带来的物性变化是CoNiGa铁磁性形状记忆合金非常有利用价值的物理性质. 相似文献
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利用X射线衍射研究了CoNiZ(Z=Si,Sb,Sn,Ga 等)合金在不同热处理条件下的相组成.当Z元素为Sn,Sb时,材料是完全的B2结构;但Z为Si时,材料变成面心立方的γ相.形成B2还是γ相由电子浓度和原子尺寸效应两种因素共同决定.而CoNiGa的研究结果表明,在合金中除了形成B2结构的同时还容易形成γ相,常表现出两相共存的特性.对材料进行不同方式的热处理可以使合金中两相的含量有所消长,γ相含量的多少对CoNiGa合金的马氏体相变有很大的影响.分析指出,两相共存及其所带来的物性变化是CoNiGa铁磁性形状记忆合金非常有利用价值的物理性质.
关键词:
Heusler合金
马氏体相变
γ相 相似文献
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T. Kojima K. Kuribayashi M. Doyama 《Applied Physics A: Materials Science & Processing》1977,12(2):179-181
The reverse martensitic transformations in Cu-23.5at-%Al, and Cu-25.3at-%Al have been studied by means of positron annihilation.
The coincidence counting rates of angular correlation were measured as a function of the specimen temperature. The change
of counting rates in heating run was rather different from that in cooling run due to the influence of tempering of martensitic
structure. The results were interpreted by the change of the formation energy of a vacancy with phase transition. Influence
of heating rate is also discussed. 相似文献
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V. N. Prudnikov A. P. Kazakov I. S. Titov N. S. Perov A. B. Granovskii I. S. Dubenko A. K. Pathak N. Ali A. P. Zhukov J. Gonzalez 《JETP Letters》2010,92(10):666-670
The Hall effect, transverse magnetoresistance, and magnetization of Ni48Co2Mn35In15 Heusler alloys have been studied at T = 77–300 K in magnetic fields up to 15 kOe. It has been shown that a martensitic transformation is accompanied by a change
in the sign of the constant of the ordinary Hall effect, which means a strong change in the electronic spectrum in the martensitic
transformation, while the anomalous Hall effect (AHE) constant is positive in both the austenite and martensite phases. In
both phases, there are no correlations between the AHE constant and the square of the resistivity, which are characteristic
of the side jump mechanism in the AHE theory. In the near vicinity of the martensitic transformation, the field dependences
of the Hall resistance are complex and nonmonotonic, indicating a change in the relative concentrations of the austenite and
martensite phases in strong fields. 相似文献
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The electrical resistivity of four lithium-magnesium alloys with magnesium concentrations of 1.0, 5.0, 10 and 20 atomic percent has been measured as the specimens were slowly cooled from 300 K to ~3 K and warmed again to 300 K. From a hysteresis in the resistivity in the region of the martensitic transformation the Ms temperatures were found. Ms increases ~5 K per atomic percent of added magnesium and, while in agreement with Dugdale and Gugan the martensite in the dilute alloy is less resistive than the high temperature (bcc) phase, it has a larger resistivity in three less dilute alloys. 相似文献
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The effect of Fe on the martensitic transformation of TaRu high-temperature shape memory alloys:A first-principles study 下载免费PDF全文
The effect of Fe on the martensitic transformation of TaRu high-temperature shape memory alloys has been investigated using first-principles calculations. The site preference of Fe in TaRu alloys has been clarified for the first time, and the results show that Fe is predicted to occupy Ru sites. The addition of Fe increases the stability of the Ta50Ru50-xFex β phase, leading to a significant decrease in the β to β′ martensitic transformation temperature. In addition, the mechanism of the Fe alloying effect is explained on the basis of the electronic structure. 相似文献
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The temperature dependences of internal friction and modulus were measured for the Fe-Mn-Si-Cr-xN alloys. A stable modulus softening of parent was newly observed to associate with the γ→ε martensitic transformation in the alloys containing certain amount (e.g. >0.086 mass%) of nitrogen, although the rather strong softening has been always recognized to occur during its reverse transformation. The enhanced strength and the increased stacking fault energy of γ matrix by nitrogen alloying are suggested to make contribution to the soft mode. 相似文献
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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
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Phonon dispersion curves for indium and f.c.t. and f.c.c. indium-thallium alloys have been calculated using the optimised model potential theory. The presence of a soft acoustic mode along [110], polarised [10] has been established. The closer the alloy composition is to the phase boundary, the softer this mode becomes: tends towards zero, in agreement with experimental ultrasonic velocity data. 相似文献
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Yu. V. Kaletina V. M. Schastlivtsev E. A. Fokina 《Bulletin of the Russian Academy of Sciences: Physics》2007,71(12):1667-1673
The effect of magnetic treatment on the isothermal martensitic transformation in the Fe-24% Ni-4% Mn alloy has been investigated. The martensitic transformation in a dc magnetic field at liquid-helium temperature has been analyzed. 相似文献
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合成了一系列Ni50-xCoxMn39Sn11 (8≤x≤10) 样品, 并对它们的结构和磁性进行了研究. 发现随Co含量的增加, 样品的饱和磁化强度逐渐增强, 并在Ni42Co8Mn39Sn11中实现了磁场诱发马氏体相变. 另外, 在Co大于8.0的成分中探测到了超自旋玻璃, 并且观察到交换偏置现象. 证实了超自旋玻璃的马氏体相和铁磁奥氏体母相共存, 这也是产生交换偏置的原因.我们猜测超自旋玻璃的形成可能是来源于Mn-Mn团簇的存在, 这和之前报道的Mn2Ni1.6Sn0.4 的结果相一致[1].
关键词:
NiCoMnSn
Heusler合金
超自旋玻璃
交换偏置 相似文献
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Ab initio phonon calculations were performed to probe the martensitic transformation of IrTi. The details of the orthorhombic structure were obtained by the soft-phonon approach. We demonstrate that the tetragonal orthorhombic (Cmmm) transition is driven by the softening of a phonon at the R point (0 ) of the Brillouin zone. The energy landscapes between the various phases of IrTi show that the structural behaviors of IrTi alloy are from cubic to tetragonal, then to orthorhombic and thus the original thought of cubic to monoclinic transition is modified. 相似文献