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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.
用熔炼和甩带的方法制备了组分为Ni50FexMn25-xGa 25(x=0—25) 的系列样品.x射线衍射实验结果表明,当Fe取代Mn的含量x<17时,用熔炼和甩带的方法均 能合成高度有序的L21结构的Heusler相.而当x>17时,普通熔炼方法只能得到 低有序度的 γ相,只有采用甩带急冷的方法才能获得高度有序的纯L21结构的化合物.根据 交流磁化率 和分子磁矩的测试结果,初步分析了Fe原子对化合物磁性的贡献,认为Fe原子占据了Mn原子 的位置后,具有高于一般含铁合金的原子磁矩,可达2.55—3.55μB.
关键词:
Heusler合金
50FexMn25-xGa25 sub>')" href="#">Ni50FexMn25-xGa25 sub> 相似文献
3.
This paper studies the martensitic transformation in the Cu-doped NiMnGa alloys. The orthorhombic martensite transforms to L21 cubic austenite by Cu substituting for Ni in the Ni50-xCuxMn31Ga19 (x=2--10) alloys, the martensitic transformation temperature decreases significantly with the rate of 40 K per Cu atom addition. The variation of the Fermi sphere radius (kF) is applied to evaluate the change of the martensitic transformation temperature. The increase of kF leads to the increase of the martensitic transformation temperature. 相似文献
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Among the series of alloys derived from Ni50Mn29Ga21 on selective substitution of Co for Ni and Mn, two alloys Ni49.8Mn27.2Ga21.2Co1.8 and Ni46.9Mn28.8Ga21Co3.3 referred to as CoMn-1.8 and CoNi-3.3, respectively, are found to exhibit an additional first-order transformation below their martensitic transformation temperatures. Systematic studies on temperature and field dependence of magnetic properties of these alloys are carried out, through the transformations, to understand their origin. An examination of these results in conjunction with those from structural investigations reveals that the transformation in the CoMn-1.8 alloy is an intermartensitic transformation and has a structural origin, while that in the CoNi-3.3 alloy is not of the structural origin and is attributed to local spin inversion of Co moments, which is of the magnetic origin. 相似文献
6.
通过研究铁磁性金属间化合物Ni2+xMn1-xGa(x=-0.1,0,0.08,0.13,0.18,0.2)和Ni2-xMn1+x/2Ga1+x/2(x=-0.1,0,0.04,0.06,0.1)两个系列多晶样品的交流磁化率随温度的变化行为,得到了化合物在不同组分下的马氏体相变温度TM和居里温度TC.发现随着Ni成分的增加,前者的马氏体相变温度Tm增加,而居里温度TC降低,后者的马氏体相变温度Tm和居里温度TC均是先增大后减小.报道了Tm在室温附近的单晶样品Ni52Mn24Ga24的磁场增强双向形状记忆效应.发现伴随着马氏体相变,样品在[001]方向可产生1.2%的收缩.如果在该方向施加1.2T的偏磁场可以使该应变值增大到4.0%.而垂直于[001]方向施加1.2T的偏磁场时,在[001]方向产生1.6%的膨胀.阐明了产生大应变的原因并非相界移动,而是单晶的杂散内应力小和外加磁场通过孪晶界移动使马氏体变体重组的共同结果.
关键词:
形状记忆效应
马氏体相变
2MnGa')" href="#">Ni2MnGa 相似文献
7.
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
8.
制备了四元铁磁性Heusler合金Co50Ni22Ga28 sub>:Fex(x=0,1.5,2,2.5),发现材料具有很好的机械性能,在加压、 弯曲和扭曲时都展现出很好的超弹性.室温时,在压力作用下,Co50Ni22< /sub>Ga28:Fe2单晶样品在[001]和[110]方向分别具有约4%和 6.7%的完全可恢复应变.Co50Ni22Ga28:Fe1.5 sub>单晶样品在室温下沿[001]和[110]方向的应力与应变σ-ε曲线的平台部分较缓, 但升温到100℃时,σ-ε曲线中表示超弹性应变的平台变平.Co50Ni22Ga28 :Fe2.5成分的单晶在[001]方向可得到5.5%的超弹性应 变.同时以上材料都显示出了明显的弹性各向异性.
关键词:
铁磁性Heusler合金
超弹性
50Ni22Ga28:Fex')" href="#">Co50Ni22Ga28:Fex 相似文献
9.
为了进一步改善材料的性能和探索新的材料,将Mn2NiGa合金中的Ni元素分别用Fe和Co替代,制备了Mn50Ni25-xFe(Co)xGa25系列合金. 研究了Fe和Co元素对Mn2NiGa合金的结构、马氏体相变行为、磁性和机械性能等方面的影响.
关键词:
铁磁形状记忆合金
Heusler合金
50Ni25-xFe(Co)xGa25')" href="#">Mn50Ni25-xFe(Co)xGa25 相似文献
10.
室温下在单晶Si中注入(0.6—1.5)at%的C原子,部分样品在C离子注入之前在其中注入29Si+离子产生损伤,然后在相同条件下利用高温退火固相外延了Si1-xCx合金,研究了预注入对Si1-xCx合金形成的影响.如果注入C离子的剂量小于引起Si非晶化的剂量,在950℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇,难于形成Si1-xC关键词:
离子注入
固相外延
1-xCx合金')" href="#">Si1-xCx合金 相似文献
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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
13.
采用基于第一性原理的密度泛函理论全势线性缀加平面波法,使用广义梯度近似处理交换相关势能,首先计算了β-FeSi2的电子结构及其各元素各亚层电子的能态密度,β-FeSi2的电子能态密度主要由Fe的d层电子和Si的p层电子的能态密度确定;其次通过计算不同掺杂系统的总能量确定了掺杂原子在β-FeSi2中的置换位置,在β-FeSi2中,Co置换FeⅡ位置的Fe原子,Al置换SiⅠ位置的Si原子,这种择位置换与现有的计算结果完全一致;最后计算了Fe1-xCoxSi2和Fe(Si1-xAlx)2的电子结构,对它们的电子结构特征进行了分析,并探讨了电子结构对其热电性能(塞贝克系数、电传输及热传输性能)的影响.
关键词:
第一性原理
电子结构
热电性能
2')" href="#">FeSi2 相似文献
14.
Effect of Co on magnetic property and phase stability of Ni--Mn--Ga ferromagnetic shape memory alloys: A first-principles study 下载免费PDF全文
The effect of Co content on magnetic property and phase stability of Ni50-xMn25Ga25Cox ferromagnetic shape memory alloys has been investigated using first-principles calculations. The total energy difference between paramagnetic and ferromagnetic state of austenite plays an important role in the magnetic transition. The high Curie temperature can be attributed to the stronger Co-Mn exchange interaction as compared to the Ni-Mn one. The phase stability of Ni50-xMn25Ga25Cox austenite increases with increasing Co content, which is discussed based on the electronic structure. 相似文献
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基于多种实验手段和能带计算的方法, 对四元合金Fe2Co1-xCrxSi的晶体结构、 磁性、输运性质及能带结构进行了研究. 研究发现, 随着Cr的增加, 合金Fe2Co1-xCrxSi保持了高度有序结构, 逐渐从Hg2CuTi结构的Fe2CoSi 过渡到L21结构的Fe2CrSi; 由于次晶格网络的破坏, 居里温度逐渐下降; 系列合金的分子磁矩呈现线性下降, 符合半金属特性; 剩余电阻比率与原子占位有序程度密切相关, 呈现两端大、 中间小的特点. 在Cr替代Co的过程中, 材料半金属能隙逐渐打开, 表现半金属特征. 同时费米能级从Fe2CoSi半金属能隙的价带顶上移至Fe2CrSi能隙的导带底. 最大的能隙宽度出现在x= 0.75处, 这表明四元合金有可能成为具有更高自旋极化率和更强抗干扰能力的自旋电子学材料. 相似文献
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N. I. Kourov V. G. Pushin 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):2471-2478
The phase composition, crystal structure, and physical properties (magnetization, electrical resistivity, thermoelectric power, relative elongation, and thermal expansion coefficient) of the stoichiometric alloy Ni50Mn25Ga25 and nonstoichiometric alloys Ni50 ? x Cu x Mn29Ga21 (x = 0, 1, 2) with the thermoelastic martensitic transformation have been investigated. The influence of the chemical composition on the transformations and physical properties of the alloys has been determined. 相似文献
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X-ray powder diffraction,resistivity and magnetization studies have been performed on polycrystalline Nd(FexMn1-x)2Si2 (0 ≤ x ≤ 1) compounds which crystallize in a ThCr2Si2-type structure with the space group I4/mmm.The field-cooled temperature dependence of the magnetization curves shows that,at low temperatures,NdFe2Si2 is antiferromagnetic,while the other compounds show ferromagnetic behaviour.The substitution of Fe for Mn leads to a decrease in lattice parameters a,c and unit-cell volume V .The Curie temperature of the compounds first increases,reaches a maximum around x = 0.7,then decreases with Fe content.However,the saturation magnetization decreases monotonically with increasing Fe content.This Fe concentration dependent magnetization of Nd(FexMn1-x)2Si2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe.The temperature’s square dependence on electrical resistivity indicates that the curve of Nd(Fe0.6Mn0.4)2Si2 has a quasi-linear character above its Curie temperature,which is typical of simple metals. 相似文献