共查询到20条相似文献,搜索用时 46 毫秒
1.
The uniaxial magnetic anisotropy Ku induced by a magnetic anneal has been determined, after stress relief, for a series of alloys given by (Fey Ni1-y )80 B20 . For all of these alloys Ku depends on anneal temperature as predicted by directional order theory. The concentration dependence of Ku in these alloys is also consistent with directional order theory. The maximum Ku , corrected for its temperature dependence, occurs at the compositiony = 0.5 . However, Ku does not fall to zero aty = 1 as predicted if directional order is assumed to arise only from Fe-Ni pair ordering. These results are interpreted as suggesting a role of the glass former, boron, in the directional ordering, perhaps as an "interstitial." The interaction energy derived from the results is negative as expected for interactions leading to precipitation. Its large value ofapprox -7.5 times 10^{-14} ergs corresponds to a critical temperature for precipitation of 3000 K. 相似文献
2.
Magnetic measurements were performed on amorphous (Fe, Ni)80 B20 , (Fe, Ni)80 B19 Si1 , and (Fe, Ni)80 P14 B6 alloy ribbons to yield the values of the magnetic moment per transition metal atom at 0 K and the Curie temperature. A close fit to the moment data, obtained by allowing not only the moments on Ni and Fe atoms to vary with Fe concentrationx , as revealed by neutron diffraction in crystalline alloys, but also the number of electrons per atom np and nb that P and B atoms, respectively, donate to the transition metald bands as described by the relationsn_{p} = 1.74 + 0.75 (1 - x) andn_{b} = 0.58 + 1.20 (1 - x) , suggests a moment of 0 andsim0.13 mu_{B} per Ni atom in amorphous Ni80 P14 B6 and Ni80 B20 alloys, respectively. The functional dependence of the Curie temperature onx , when followed closely for low Fe concentrations, gives the critical concentration xc above which ferromagnetism appears in amorphous Fex Ni80-x B20 and Fex Ni80-x P14 B6 alloy series asx_{c} cong 5 and 8 at % Fe, respectively. The results of a theory based on coherent-potential approximation have been fitted to the measured values of Curie temperature in order to arrive at the Fe concentration dependence of the exchange interaction (JNiNi ) between Ni-Ni pairs. The physical significance of the variation of JNiNi withx obtained thereby has been discussed. 相似文献
3.
Field annealing experiments on amorphous Fe80 B20 ribbon (Metglas 2605) and amorphous Fe78 Si10 B12 ribbon (Tsuya, Tohoku University) are reported. The maximum magnetomechanical coupling constant,k , and change in Young's modulus, ΔE/E0 found in Fe80 B20 were 0.64 and 0.87, respectively, for an anneal of 376° for 6 min in a field of 2.0T. The maximumk for Fe78 Si10 B12 was found to be 0.82, following a similar anneal at 373°C. This is higher than 0.75 reported by Tsuya and Arai for Fe78 Si10 B12 , previously the highest known for any material. 相似文献
4.
The crystallization temperatures, magnetic properties, and density of amorphous alloys of Fex By Siz Cz are reported for72 < x < 88, 16 < y < 28 , and0 < 2z < 12 . The peak value of 4 ± Ms is 17 kG in the as-cast state and occurs in the region of Fe82 B13 Si2.5 C2.5 . The crystallization temperatures, Curie temperatures, saturation magnetization, and density all appear to be average values of the ternary Fe-B-Si and Fe-B-C properties. 相似文献
5.
Measurements of the upper critical fields are presented for ternary metal-molybdenum-sulfides as a function of temperature, T, with dc magnetic fields up to ∼215kG and pulsed fields to ∼500kG. A nearly linear variation of HC2 versus T is observed up to the highest dc fields for all the compounds. The materials (nominal composition), Tc (measured);(dH_{C2}/dT)_{T=T_{c}} (measured), and HC2 (4.2 K) (calculated) for a dirty type II superconductor assuming no paramagnetic limiting are respectively: (a) Pb0.9 Mo5.1 S6 : 11.7 K, 60 kG/K, 390 kG; (b) SnAl0.5 Mo4.5 S6 : 14.2 K, 32 kG/K; 275 kG; (c) SnMo5 S6 :13.4K, 37kG/K; 290 kG; (d) PbMo5.1 S6 : 14.4, 60kG/K, 515kG. Pulsed field measurements yield HC2 (4.2 K) = 390 kG for (a), 275 kG for (b), 290 kG for (c), and ≃510kG for (d). The PbMo5.1 S6 has the highest value of HC2 measured to date. 相似文献
6.
《IEEE transactions on magnetics》1979,15(4):1146-1149
The magnetic properties and crystallization temperatures of alloys in the ternary Fe-B-Si system are reported. The Curie temperature increases slightly on replacement of boron by silicon. This results in a sharp ridge of relatively constant room-temperature saturation magnetization extending from Fe80 B20 to Fe82 B12 Si6 . The coercivity exhibits a broad minimum, both before and after stress relief annealing, in the region around Fe81 B15 Si4 and extending at least to Fe77 B13 Si10 . The crystallization temperature increases with increasing silicon and with decreasing iron and boron. The alloys with silicon are generally easier to prepare in the amorphous state than the binary Fe-B alloys. Thus for the highest saturation magnetization alloy combined with ease of preparation, stability, and lowest losses, the alloys between Fe81 B17 Si2 and Fe82 B12 Si6 are preferred. 相似文献
7.
《IEEE transactions on magnetics》1965,1(4):285-292
In an all-magnetic resistance-type shift register, a PRIME current pulsei_{p}(t) , of amplitude Ip , is applied to Np and Nb turns through the minor and major apertures, respectively. For given operation frequencyf , the ratioR = I_{p}^{max}/I_{p}^{min} , whereI_{p}^{min} < I_{p} < I_{p}^{max} is the PRIME range of bistable operation, is maximized by matchingN_{p}/N_{b} so thatI_{p}^{max} values determined by spurious ZERO buildup and ONE dropout are the same. For a rectangular (or dc)i_{p}(t) , the matchedN_{p}/N_{b} is fixed by the core properties, and Rmaxis limited (e.g., <7). However, ifi_{p}(t) rises gradually, the matchedN_{p}/N_{b} depends also on the rise time Tr ofi_{p}(t) . The lowerf is, with corresponding larger Tr , the smaller is the matchedN_{p}/N_{b} , and the larger is Rmax. Calculation ofR is carried for ramp and half-sinusoidali_{p}(t) waveforms. The latter, for instance, atT = 25deg C yields Rmaxvalues of 14.0 and 22.0 forf of 1.0 and 0.5 kc/s respectively. Such wide PRIME ranges permit reliable register operation in a wide temperature range without resorting to temperature compensation of Ip . Experimental results are in agreement with the calculation. 相似文献
8.
When mechanical forces are applied to single domain particles that are used in magnetic recording tapes, the resultant stress anisotropy energy alters the magnetized state, producing reversible and irreversible changes. We use four different experimental techniques to measure these changes and analyze the results in terms of the values for the saturation magnetostriction constants (λs ) and the applied stress (σx ). The reversible changes in magnetization (Mx ) are roughly proportional tolambda_{s}sigma_{x} ; the greatest irreversible or loss component occurs when the product of σx and λs along the magnetizing axis (x ) is negative, increasing when major easy axes make large angles withx . 相似文献
9.
The chill-cast alloy, Fe75 Si15 B10 , consists of submicron rods of Fe2 B, a magnetically "hard' phase with high Tc , in a matrix of Fe3 Si, a "soft" phase with low Tc . Magnetic properties change markedly on cooling through 590°C, the Tc of Fe3 Si, and 245°C, where the magnetocrystalline anisotropy of Fe2 B changes from easy-axis to easy-plane. The unusual magnetic and thermomagnetic behavior observed is discussed in terms of the short-range and long-range magnetostatic interactions between the two phases. 相似文献
10.
Magnetic properties of evaporated CoCr films 总被引:1,自引:0,他引:1
Perpendicular magnetic CoCr films were prepared on glass substrates using electron beam evaporation. The magnetic properties depend strongly on the substrate temperature, Ts . The anisotropy field,H_{k}^{eff} , and the perpendicular coercivity, Hc (perp ) show maximum values at Ts around 250°C. In this case, the alignment of c-axis is optimal and the grain size is smallest. The lattice spacing of the c-planes increases wlth Ts until 300°C. When the films prepared below 200°C were annealed around 300°C in high vacuum, the saturation magnetization, Ms , increased. The value of Ms , however, decrease by annealing above 400°C. In spite of the decrease of Ms due to the annealing above 400°C,H_{k}^{eff} and Hc (perp ) increase by annealing above 400°C. If the films were bombarded by argon ions during film growth, Ms decreased and the internal stress changed from tensile to compressive. For low substrate temperature (below 150°C),H_{k}^{eff} decreased due to ion bombardment. 相似文献
11.
Experimental evidence is cited that, for very small hysteresis loops, the remanent magnetic flux density Br is not proportional to the square of the amplitude of the magnetic field excursion H1 (as given by the Rayleigh relation), but rather to the first power. It is shown that (subject to one very general assumption), were this dependence exact, it would lead to negative hysteresis loss. It is also shown that (subject to the same assumption) any power-series dependence ofB onH will always giveB_{r} propto Hmin{1}max{2} . An approximate first-power dependence is found to follow naturally from the spring model. A new Rayleigh relation is proposed which contains a logarithmic term which may not be expanded in a power series about zero argument. 相似文献
12.
The anhysteretic remanencebar{M}_{ar}(H_{o},T) of solidified suspensions of magnetic particles with predominant shape anisotropy is calculated from first principles for small dc fields Ho and arbitrary temperatureT < T_{B} (blocking temperature), describing the particle interactions by a mean field and assuming constant decrement of the ac field,2H_{d} per cycle. ForH_{d}< 2H_{o} , the anhysteretic distribution of particle magnetizations is found to be subject to the condition that the net internal dc fieldbar{H}_{i} is a minimum, and, for small Ho , to the condition,bar{H}_{i} = 0 . The theory yieldsbar{M}_{ar}(H_{o},T) as a unique function of independently measurable static magnetic material properties, i.e., it contains no adjustable parameters and is hence quantitatively related to experimental data. Further, according to theory, ifbar{M}_{ar}(H_{o},T,T_{m}) denotesbar{M}_{ar} as acquired in Ho at T and measured atT_{m}, bar{M}_{ar}(H_{o},T,T_{m} = T) is independent ofT forH_{d} ll 2H_{o} , andbar{M}_{ar}(H_{o},T,T_{m} neq T) = [M_{s}(T_{m})/M_{s}(T)] cdot bar{M}_{ar}(H_{o},T,T_{m} = T) . The thermoremanent magnetization acquired in Ho and measured at a temperatureT_{m} ll T_{B} ,bar{M}_{thr}(H_{o},T_{m}) , is related tobar{M}_{ar}(H_{o},T = T_{m}, T_{m}) bybar{M}_{thr}(H_{o},T_{m}) = [M_{s}(T_{m})/M_{s}(T_{B})]bar{M}_{ar}(H_{o},T=T_{m},T_{m}) , where TB is the blocking temperature below whichbar{M}_{thr} becomes thermally stable. Up to a constant factor of about 2, the theoretical results agree quantitatively with the experimental data on all materials that correspond to the premises of the theory, i.e., solidified suspensions, tapes in particular, of particles having predominant shape anisotropy. 相似文献
13.
Amorphous alloy films, mainly composed of Co-Nb, have been studied by radio frequency (RF) sputtering. These amorphous films having small magnetostriction show excellent soft magnetic properties after the magnetic annealing we have developed. One of them with the composition of (Co83.5 Fe2 )92/85.5 Nb8 was found to have very high saturation magnetizationB_{s} = 14300 (gauss). The effects of additives such as Zr to the alloys have been investigated and amorphous films having high crystallization temperature as well as high saturation magnetization were successfully obtained. These amorphous films show fairly good wear and corrosion resistance as well as excellent thermal stability of the magnetic properties. 相似文献
14.
Demagnetization curves were recorded for composites of 1) Co5 Sm and Lodex, 2) Co5 Sm and lead, and 3) two different Co5 Sm powders of widely different Hci values. "Kinks" observed for the first and third composites but not the second show that the effect results from the difference in Hci . The Co5 Sm-Lodex composites produced "kinks" in only the 20-80 wt % Lodex range. Significant improvement of energy product in Lodex composites requires more than 70 wt % of Co5 Sm. Better results can be obtained by diluting Co5 Sm with lead. For applications operating at high load lines and requiring high inductions, improved properties may be obtained by small additions of Co5 Sm to Lodex. Energy product and Hci can be improved for Co5 Sm-lead composites by zinc coating the magnetic particles prior to pressing. One sample producedBH_{max} values of 7.5 MGOe and Hci of 13.5 kOe. 相似文献
15.
Superconducting Nb3 Sn Cavities have potential advantages over rf cavities with Nb surfaces To test possible applications and to improve the understanding of Nb3 Sn coatings on Nb, rf cavities have been measured between 1.5 and 8K and between 0.1 and 7GHz. The temperature dependence of the surface resistance R(T) indicates weak superconducting spots with transition temperaturesTmin{c}max{ast} < 1 K andTmin{c}max{ast} simeq 2.5 K. The normal conducting spotsTmin{c}max{ast} lsim 1 K cause the large rf residual lossesR'_{res} propto f^{2} observed up to date. The spots withTmin_{c}max_{ast} simeq 2.5 K cause temperature dependences ofR'(T) between 2 and 6K, where RBCS (Nb3 Sn) is still negligible. In line withR_{res} propto f^{2} , the lowest rf lossesR_{res} < 2.10^{-9}Omega and the highest field strengthB_{crit} = 83 m^{T}(wedgeE_{peak} = 29have been observed at the lowest frequency 0.1GHz measured. Surface resistance and penetration depth measurements have shown that grain boundaries or hydrogen clusters do not cause the weak spots observed withTmin{c}max{ast} < 2.5 K. The origin and the chemistry of the weak spots withTmin{c}max{ast} lsim 1 K, which cause the largeR_{res} propto f^{2} and the lowB_{crit} (T) simeq const , are still not clear. They seem related to the Nb3 Sn surface. The weak spots withTmin{c}max{ast} simeq 2.5 K consist most likely of Nb6 Sn5 , which in cooling below 950°C precipitates due to the excess Sn present in Nb3 Sn coatings grown in Sn vapor. 相似文献
16.
Powders of a misch metal-cobalt alloy of type (MM)Co5 were prepared and consolidated in various ways to study the effects of particle size, plastic deformation during milling, and pressure applied during compacting on the permanent magnet properties. Vibration grinding yields particles with high coercive force (M H_{c} = 4180 Oe) but which align very poorly in a field. Mortar-ground powders have high magnetic anisotropy combined with much lower, but strongly particle-size dependent Hc . Ballmilling, a method suitable for production in quantity, constitutes a satisfactory compromise. Pressing ballmilled powder in a field with 3400 kg/cm2pressure and no binder gave optimum results. A magnet havingM H_{c} = 2010 Oe,B H_{c} = 1620 Oe,B_{r} = 4060 G, and(BH)_{max} = 2.34 MG.Oe was obtained. Details of the static and recoil behavior for this magnet are reported. 相似文献
17.
An experiment was carried out to investigate the preparation condition of anisotropic Ca system ferrite magnets with optimum magnetic and physical properties. Compositions were chosen according to the formula (CaO.nFe2 O3 )100-x (La2 O3 )x , wherex was varied between 0 and 4.0, and n between 5.5 and 6.25. The optimum condition of making magnets and some properties of a typical specimen are as follows. The preparation condition: composition (CaO.6Fe2 O3 )97 (La2 O3 )3 , semisintering condition 1250°C × 1 h in O2 gas, sintering condition 1275°C × 0.5 h in O2 gas. Magnetic properties:4piI_{10}k = 4200 G, 4πIr = 4100 G,I HC = 2100 Oe,B HC = 2050 Oe,(BH)_{max} = 3.5 MG . Oe, Ku = 3.34 × 106erg/cc, HA = 20.5 kOe,sigma_{s} = 64.8 emu/g, Tc = 446°C. 相似文献
18.
The gadolinium garnet system {Gdz Y3-2x-z Ca2x } [Fe2-y Iny ] (Fe3-x Vx )O12 was investigated as a function of x, y, and z for0 leq x leq 0.6, 0 leq y leq 1.0 , and0 leq z leq 2.4 . The relationships between their compositions and magnetic properties were clarified. It was shown that some combinations of components in this system displayed improvements with respect to temperature stability (alpha = 0.05 %/°C-20 sim 60 deg C) and ferromagnetic resonance linewidth (ΔH = 20 ∼ 30 Oe) as compared with conventional garnets. 相似文献
19.
Co-Fe-Cu-Ce permanent-magnet alloys have been prepared by directional solidification using a modified Bridgman technique. Samples melted at low superheat temperatures (DeltaT sim 20deg C above the melting point of about 1100°C) and solidified at moderate rates (∼2.3 cm/h) resulted in a reasonably homogeneous columnar grain structure with a preferred crystallographic orientation. Thec axis is generally aligned within 15° of the growth axis. Increasing the speed of solidification led to a fine-grained structure with no texture, while decreasing the speed led to coarse columnar grains with erratic orientation. A large superheat temperature (DeltaT sim 300-400deg C resulted in a reaction of the liquid with the alumina crucible wall and led to the formation of face-centered cubic Co-rich dendrites. With the modified Bridgman technique, oriented samples 8 cm long and 2.54 cm in diameter have been prepared with good magnetic properties. After annealing at 1000°C followed by aging at 400°C, a Co3.5 Fe0.5 CuCe alloy exhibited values ofi Hc = 7000 Oe, Br = 6100 G, and(BH)_{max} = 9.2 MG.Oe. A Co3.6 Fe0.5 Cu0.9 Ce alloy exhibited values ofi Hc = 6000 Oe,B_{r} = 6250 G, aud(BH)_{max} = 9.5 MG.Oe after similar treatment. 相似文献
20.
Low temperature fatigue effects on residual resistivity ratio (RRR = rho_{273 K}/rho_{4.2K} ) and strength of 300 and 1000 RRR aluminum are reported. The objective of this investigation is to select the best initial purity for the stabilizer aluminum used in energy storage magnets. Monolythic centimeter diameter specimens were fatigued at 4.2 K to strains (ε) reaching 0.3 percent. The resistivity ratio rapidly decreases during the first 100 cycles and approaches saturation (RRRf ) after about 1000 cycles for all strains tested. The RRRf values are different for different initial resistivity ratio (RRRi ) values, but all tend to come together at 0.3% strain independent of RRRi . The maximum specimen stress (sigma_{max} ) is reached after about 1000 cycles also, and approaches a common value (sigma_{max} = εE/2 , where ε is the strain range and E the elastic modulus) independent of RRRi . Thus high purity aluminum becomes "fully hard" at equilibrium and behaves elastically. The impact of fatigue damage on conductor design and choice of stabilizer purity is considered. 相似文献