共查询到19条相似文献,搜索用时 343 毫秒
1.
在600-930K,常压到7GPa的范围内,对非晶(Fe0.99,Mo0.01)78Si9B13合金等温等压退火30min。实验表明;其晶化产物α-Fe(Mo,Si)Fe3B和Fe2B相的析出与所加压力密切相关。压力使非晶(Fe0.99Mo0.01)78Si9B13合金的晶化温度和亚稳Fe3B相的析出温度下降,在一定的压力和温度下,亚稳Fe3B相半向稳定Fe2B相转变其转变温度随压力而变化。 相似文献
2.
3.
4.
研究了500和600℃真空退火后的纳米晶Fe38.4Co40Si9B9Nb2.6Cu合金初始磁导率随温度的变化规律,发现较高温度(600℃)退火的FeCo基纳米晶合金,在非晶相居里温度以上较宽温度范围内磁导率没有明显的衰减,这是在双相纳米晶合金中观察到的一种新现象,其磁特性不同于Fe基纳米晶合金.为了探明这种现象的起源,估算了与剩余非晶相同成分的非晶合金的居里温度及纳米晶粒间发生交换耦合作用的参数
关键词:
交换耦合作用
非晶相居里温度
交换耦合穿透深度 相似文献
5.
6.
7.
8.
9.
10.
用内转换电子穆斯堡尔谱(CEMS)和慢正电子束研究了含3%Y2O3的ZrO2中57Fe离子(100keV,3×1016at./cm2)注入态及其在氢气氛中退火的热力学行为.注入态以Fe3+,Fe2+和Fe0存在,它们分别是Fe3+-V(空位)复合体、二聚体和超顺磁颗粒.经400,500℃退火后,Fe3+-V分解,分别出现了α-Fe的前期相和α-Fe纳米颗粒.含Fe的ZrO2(Y)混合导电的出现可能是和Fe的不同价态及其相对含量有关
关键词: 相似文献
11.
Measurements of magnetization, electrical resistivity, thermal expansion and differential thermal change were made on amorphous Fe100-xBx (9 ≦ X ≦ 21) alloys prepared by rapid quenching from the liquid state.With decreasing boron content in the alloys, the Curie temperature falls remarkably, while the magnetic moment increases sluggishly. The thermal expansion curves exhibit the invar characteristics below the Curie temperature due to a large positive spontaneous volume magnetostriction, and the reduced magnetization curves decrease much more rapidly with increasing temperature than those of other ferromagnetic amorphous alloys. 相似文献
12.
The magnetic behavior of nanocrystalline Fe73.5Nb4.5Cr5B16Cu1 alloys is investigated in a series of specimens with different volume fractions of crystalline phase. It is shown that the Curie temperature of amorphous phase firstly decreases after structural relaxation in amorphous state and then rapidly increases during the first stages of crystallization. The strikingly different behavior of coercivity at elevated temperatures is observed for the samples with low and high volume fractions of nanocrystalline particles. 相似文献
13.
A.K. Panda Seema KumariI. Chattoraj M. GhoshA. Mitra 《Journal of magnetism and magnetic materials》2007
The investigation addresses the electron transport properties of Co71−xFexCr7Si8B14 (x=0, 2, 3.2, 4, 6, 8 and 12 at%) amorphous alloys. The variation in electrical resistivity of as-cast amorphous materials with thermal scanning from room temperature to 1000 K was measured. The CoFe-based alloys revealed an initial decrease in temperature coefficient of resistivity (TCR), a characteristic of spin-wave phenomena in glassy metallic systems. This behaviour in the present alloys was in a sharp contrast to the Co-based amorphous materials that indicate the drop in resistivity much below room temperature. In the studied alloys, the variation in initial TCR values and the full-width at half-maxima determined from X-ray diffraction of as-quenched materials exhibited a similar trend with increasing Fe content, indicating the compositional effect of near neighbouring atoms. After the initial decrease in resistivity, all the alloys indicated a subsequent increase at Tmin. The Curie temperature (TC), which was measured from thermal variation of ac susceptibility showed non-monotonic change with Fe content. In the temperature range between Tmin and TC the relative scattering by electron-magnon and electron-phonon resulted in the non-monotonic change in Curie temperature. At crystallization onset (TX1) all the alloys except there with X=6, showed a sharp decrease in electrical resistivity which was attributed to ordering phenomena. In contrast to this resistivity decrease, X=6 alloy exhibited a drastic increase in resistivity around TX1 observed during amorphous to nanocrystalline transformation. Such nanocrystalline state was observed by Transmission electron microscopy. 相似文献
14.
15.
J.M. Greneche 《Hyperfine Interactions》1997,110(1-2):81-91
Nanocrystalline alloys exhibit great fundamental and technological interests because of their microstructural properties, and their excellent soft magnetic properties. 57Fe Mössbauer spectrometry is a well suitable technique to investigate Fe-based nanocrystalline alloys: its local probe behaviour permits to elucidate the nature of hyperfine interactions at different resonating iron nuclei and to distinguish their immediate atomic surroundings. We review on the recent Mössbauer developments performed on first FeCuMBSi and then FeCuBSi nanocrystalline alloys. From Mössbauer studies, one can estimate the crystalline (i.e., amorphous) fraction, the Si-content in Fe--Si nanocrystalline grains emerging from amorphous alloys of the first series, the temperature dependence of magnetic behaviours of both crystalline and amorphous phases; finally, we present a novel fitting procedure applied to FeCuBSi nanocrystalline alloys which result from bcc-Fe crystalline grains embedded in an amorphous matrix. In this case, the hyperfine structure is able to model the intergranular phase. 相似文献
16.
《Journal of magnetism and magnetic materials》2003,267(3):307-315
Rapidly solidified (RS) Nd2Fe14B alloys were prepared by melt-spinning under different melt treatment conditions i.e., the melt temperature was varied prior to ejection onto the quenching wheel. X-ray diffraction, transmission electron microscopy, thermal analysis and magnetic measurement were conducted on the as-quenched alloys to investigate their structural and magnetic characteristics. RS Nd2Fe14B alloys may display a variety of microstructures depending upon the thermal history of the melt before ejection: it was possible to synthesize an entirely amorphous structure, a partially amorphous structure containing nuclei and/or nanophases and a nanocrystalline structure. The relationship between the formation of crystalline nuclei or nanophases and the thermal history of the melt was studied. A lower melt ejection temperature produced a nanocrystalline microstructure, while higher melt ejection temperatures (T>1723 K) largely eliminated the presence of nuclei and associated nanophases and produced an amorphous product. The experimental results indicated that optimization of the melt treatment conditions will produce rapidly solidified Nd–Fe–B alloys with a more uniform microstructure. 相似文献
17.
N. Ponpandian A. Narayanasamy D. Prabhu K. Ganesan M. Manivel Raja K. Chattopadhyay 《Journal of magnetism and magnetic materials》2006
The Fe73.5Cu1Nb3Si13.5B9 FINEMET alloy has been prepared by the rapid solidification technique. The critical behaviour of this alloy in the amorphous as well as in its nanocrystalline states has been studied near their respective Curie temperatures. From the values of the critical exponents one can conclude that the alloy behaves like a 3D Heisenberg ferromagnet in the amorphous and nanocrystalline states. But there exists a slight increase in the value of β for the alloy annealed at 823 K (the nanocrystalline state) as observed in most of the amorphous alloys. 相似文献
18.
E. Kuzmann A. Vértes Y. Ujihira M. Fujinami P. Kovács S. Nagy T. Masumoto 《Hyperfine Interactions》1988,42(1-4):939-942
Mössbauer spectroscopy was used for studying the effect of hydrogenation on amorphous Fe90Zr10 and Fe89Zr11 alloys electrolytically charged to high hydrogen content. The differences observed between the room temperature Mossbauer spectra of uncharged and hydrogenated amorphous alloys can be attributed to a change in the Curie temperature. Up to a certain hydrogen content the Curie temperature increases with the hydrogen concentration while the Curie temperature goes thorough a maximum as the hydrogen content increases. 相似文献
19.
Magnetic systems with a considerable amount of irregular interfaces were investigated by 57Fe Mössbauer spectroscopy. Chemically homogeneous ferromagnets around the percolation threshold composition of disappearing magnetism and chemically heterogeneous alloys prepared by nanocrystallization of amorphous alloys belong to this class of materials. Low temperature and high field measurements were performed on nanocrystalline FeZrBCu alloys, on ball‐milled Fe with nano‐size grains and on melt‐quenched amorphous Fe–Zr and Fe–Y alloys in order to clarify the origin of large high‐field susceptibility and to investigate the common features of the approach to magnetic saturation. Curie point determination of the residual amorphous phase in the nanocrystalline FeZrBCu alloys, results on the structure of the nanocrystalline b.c.c. phase and of the interfacial region will be reported. 相似文献