摘要:

Variations in the number and mobility of domain walls have been proposed as explanations for the frequency dependence of losses in 3% Si‐Fe. In order to test these explanations, the domain structure in (110)[001] grain‐oriented 3% Si‐Fe was photographed during transversal of individual magnetization cycles using high speed Kerr cinematography. Measurements of wall velocity revealed a dependence of wall mobility on magnetizing frequency over the frequency range from 0.1 to 10 Hz with no change in the number of walls. From 10 to 100 Hz, the number of walls increased; however, the rate of increase was less than that predicted, and the newly created walls were not present during the entire magnetization cycle.

ISSN:0094-243X    

DOI:10.1063/1.2953902

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Some features of the Barkhausen effect in randomly oriented, polycrystalline rods of Fe‐3. 2% Si have been studied by the inductive search coil method utilizing pulse height analysis. For the annealed condition, the number, NT, and average amplitude, ⟨h⟩, of Barkhausen pulses were found to be essentially independent of elastic tensile strain, but to increase markedly with elastic compressive strain. The values of NTand ⟨h⟩ increased monotonically with plastic tensile strain, being significantly greater for the unloaded state compared to the loaded state. A pronounced minimum was observed in the distribution of Barkhausen jumps along a branch of the hysteresis loop. The results are tentatively interpreted in terms of two different jump mechanisms.

ISSN:0094-243X    

DOI:10.1063/1.2953903

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Glass coatings having low coefficients of thermal expansion were applied to mill‐coated oriented silicon steel strips. By imparting residual tensile stress to the steel, the glass coatings resulted in a substantial decrease in the strain sensitivity of 60 Hz core loss and dc magnetostriction under conditions of applied bending stress.

ISSN:0094-243X    

DOI:10.1063/1.2953904

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Transfer impedance measurements are performed on several Ni&sngbnd;Fe tubes over the frequency range of 10 to3.2 × 107hertz. The influence of axial dc magnetic fields is studied. A limiting nonlinear model is devised to explain and predict the behavior of soft magnetic material used to shield against current in coaxial configurations. The new model relates to the basic dc magnetic and electrical properties of the material, saturation induction, initial permeability, electrical conductivity and the magnitude of the applied magnetic field.

ISSN:0094-243X    

DOI:10.1063/1.2953905

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Secondary recrystallization in 50% nickel‐iron alloys results predominantly in {112} and {120} textural components. The beneficial effects of {120} textures on the magnetic properties of toroidal wound cores have been reported, and the effects of impurities and surface energies in promoting {120} growth have been discussed in the technical literature. Therefore, an understanding of the mechanism of secondary recrystallization in these alloys is pertinent. A strong {100}⟨001⟩ texture is developed by the primary recrystallization of cold rolled 50% nickel‐iron. It is demonstrated in the present study that during heat treatment the non‐coherent boundaries of {221} first order annealing twins partially or completely sweep adjacent grains in the {100}⟨001⟩ textured matrix to produce enlarged grain segments in the {221} orientation, and it is proposed that the {221} grains are the nuclei for secondary recrystallization. On further annealing an incubation period occurs during which essentially no growth of the {221} grains is observed. During eventual secondary recrystallization the {221} grains, after some growth, twin massively to form the predominant secondary orientations, {112} and {120}. The {112} and {120} secondaries, therefore, bear a second order twin relationship with the {100}⟨001⟩ primary matrix. The boundaries of the {112} and {120} twins are not coherent with the matrix and consequently migrate very rapidly.

ISSN:0094-243X    

DOI:10.1063/1.2953906

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Ductile alloys which have approximately equal amounts of Co and Fe, plus Ni and a small amount of Nb were investigated for remanent reed switch applications. As a result, 39Fe&sngbnd;38Co&sngbnd;20N&sngbnd;3Nb wire 0.6mm in diameter, made by intermediate annealing at 700°C, cold drawing to 92% reduction in area, and final annealing at 6007deg;C for 1 hour, showed a coercive force of 30 Oe, remanence of 16000 G, squareness ratio higher than 0.95, and thermal expansion coefficient of98×10−7/°Cbetween 30 and 400°C. This alloy could be cold‐worked easily after annealing. The phase was f.c.c. after annealing at a temperature over 800°C. However, cold working caused partial phase transformation of f.c.c. into b.c.c. This intermixing of f.c.c. and b.c.c. phases in a high coercive force state survived up to 700°C annealing. On the other hand, remanence was low in the cold drawn state, but increased by annealing over 600°C. The coercive force grew larger as the Nb content increased.

ISSN:0094-243X    

DOI:10.1063/1.2953907

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Dilatometric measurements were obtained on Vanadium Permendur in view of its reported instability above 500C. Contrary to the results of other investigators, heating a specimen initially in the ordered condition to 850C and cooling to room temperature did not show a permanent change in length. However, heating to 1000C or above, just into the austenite field, and cooling to room temperature resulted in a peimanent decrease in length of about6×10−4 cm./cm. Each of several subsequent cycles resulted in an additional decrease in length. In addition to this change, the dilatometric curves showed other discontinuities. As expected the order‐disorder transformation occurred at 700C. The curves also showed a maximum and minimum slope at about 490C and 540C respectively. The reason for these changes in the slope remains to be determined.

ISSN:0094-243X    

DOI:10.1063/1.2953908

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We have made in‐plane ferromagnetic resonance measurements at X‐band on single crystal YIG discs epitaxially grown on GGG substrates. The in‐plane resonant fields of the magnetostatic spectrum were measured as a function of aspect ratio, temperature, angle, and crystal plane ([110] or [100]). The aspect ratio ranged from 25 to 500 while the temperature of the samples was held at 77°K, and 300°K.

ISSN:0094-243X    

DOI:10.1063/1.2953909

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The present paper is devoted to a study of TE surface modes along a ferrite‐dielectric interface, the ferrite magnetization being parallel to the interface. For a transverse propagation with respect to magnetization, two TE‐modes can be found. These unidirectional modes are respectively forward and reverse. The “magnetostatic mode” includes the Damon‐Eshbach mode. The “dynamic mode”, which presents a very wide bandwidth, includes the mode recently described by Hines. Our investigation, carried out on a schematic configuration, gives simple results, which clearly point out the physical behaviour of these very interesting modes.

ISSN:0094-243X    

DOI:10.1063/1.2953910

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The magnetization and anisotropic properties of single crystal Co and Cu‐18H‐layer hexagonal ferrites are reported. Magnetization measurements of these microwave materials were made from 4.2°K to Tcin fields up to 15 kOe. While theCo‐18Hhas an easy plane and Cu‐18H has an easy axis (c) of magnetization,Ea = K1sin2&thgr; + K2sin4&thgr;is applicable to both. The magnetization of Co‐18H was saturated at all temperatures and exhibited a Ne´el M type Msvs T curve. In hysteresis loops of Cu‐18H above 58°K constrictions were present. In sharp contrast to barium ferrite, Hcvs T decreases exponentially. The Tcvalues are495±6°Kand530±8°K, respectively for Co and Cu‐18H. A moment for Co‐18H,n&bgr;(H=∞, T=0) = 9.6&mgr;&bgr;was found.

ISSN:0094-243X    

DOI:10.1063/1.2953911

出版商:AIP    

年代:1972

数据来源: AIP