摘要:

Two major aspects of the soft magnetic properties of metallic glasses, i.e., high magnetic permeability and high saturation induction, are discussed. Recent development in the area of high permeability materials is centered around the zero‐magnetostriction Co‐rich metallic glasses having Si and B as metalloids. The heat treated materials studied thus far show low‐field magnetic properties comparable or superior to those of commercial supermalloy. A typical example includes an effective permeability at l kHz exceeding 50,000. Attractive high saturation induction metallic glasses are found in the series Fe82B18−xSix. Typical dc results for field‐annealed samples of this glass with x=8 are Hc=0.03 Oe, Br=12 kG and &mgr; (20) =8,000. Core loss under sine flux conditions at 60 Hz is 0.24 watts/kg at 16 kG. This value is nearly five times lower than that of the widely used power transformer material grade M‐4 Si/Fe (1.3 watts/kg) and well below that of Fe‐B glass. The stability against crystallization of Fe82B10Si8is higher than that of Fe80B20.

ISSN:0021-8979    

DOI:10.1063/1.327255

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Amorphous superconducting materials were first prepared over twenty years ago by Buckel and Hilsch [1] using the technique of evaporation onto a cryogenically cooled substrate. Since this early work on simple metals, such studies have been extended to transition metal thin films and more recently to bulk metallic glasses prepared by rapid cooling of liquid metals. This article presents a brief survey of current experimental work on amorphous transition metals and alloys. The relationship between superconductivity and microscopic electronic structure is emphasized. Results of structural studies, magnetic susceptibility and specific heat measurements, photoemission spectroscopy, transport measurements, and superconductive tunneling experiments are covered. The role of structural disorder in determining the nature of the superconducting state is discussed, and possible technical applications of these materials which exploit their unique properties are pointed out.

ISSN:0021-8979    

DOI:10.1063/1.327256

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Recent advances in the technique of energy dispersive X‐ray diffraction (EDXD) have made it possible to study the atomic structure of amorphous solids with greater accuracy. This paper reviews the techniques involved in the successful utilization of the EDXD method. Also the structural relaxation of amorphous alloys which was recently clearly resolved by the EDXD technique is discussed, as well as the structure of the Fe‐B‐C amorphous alloys, which were found to have the highest room‐temperature saturation induction among the Fe based amorphous alloys.

ISSN:0021-8979    

DOI:10.1063/1.327257

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Various properties of amophous ferromagnetic materials containing transition metal and metalloid atoms are reviewed. These point clearly to an itinerant electron model description of the materials. (AIP)

ISSN:0021-8979    

DOI:10.1063/1.327258

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Amorphous Fe84B16−xCx(0?x?10) have been studied by57Fe Mo¨ssbauer spectroscopy. The Curie temperature (TC) increases monotonically with carbon concentration. Well‐defined hyperfine field distributions {P(H) } at 4.2 K have been found. The distribution width as well as the asymmetry of P(H) increase smoothly as carbon replaces boron. The mean hyperfine field and the average iron moment are found to be proportional. There is a small change in the temperature dependence of the reduced hyperfine field as the carbon concentration increases. This suggests the distribution width of the exchange interactions varies slightly with carbon concentration.

ISSN:0021-8979    

DOI:10.1063/1.327259

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Amorphous (FexMo1−x)75P16B6Al3with x=0.7, 0.8, 0.9, 0.95 and 1.0 have been studied by57Fe Mo¨ssbauer spectroscopy. The magnetic ordering temperature decreases drastically from 640 K for x = 1.0 to 26 K for x = 0.7. The result suggests an antiferromagnetic exchange interaction between Fe and Mo. Anomalous magnetic hyperfine interactions have been observed at 4.2 K. The P(H) analyses indicate a two‐maxima function of H. The intensity of the low‐field component increases with Mo content and at the expense of the high‐field component. This indicates that there is a substantial number of Fe atoms which are weakly magnetic or have small moments.

ISSN:0021-8979    

DOI:10.1063/1.327260

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

High pressure–Mo¨ssbauer studies to 110 kbar on Metglas 2826A are reported. It is found that both Tcand the hyperfine field reduce monotonically with increasing pressure. In contrast to other metglas materials a paramagnetic component is observed at temperatures well below Tc. The splitting of this weaker component roughly follows the temperature and pressure dependence of the hyperfine field observed for the main component.

ISSN:0021-8979    

DOI:10.1063/1.327261

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We have used ferromagnetic resonance to measure the temperature dependence of the saturation magnetization in three glassy alloys: I: Fe29Ni49P14B6Si2(Metglas 2826B), II: (Fe0.4Ni0,6)75P16B6Al3, and III: (Fe0.5Ni0.5)75P16B6Al3. In I we find that, for 4 ?T?300 K, the magnetization follows the relaxation M(T) =M0(1–BT3/2−CT5/2) with B and C values fairly close to those obtained using Mo¨ssbauer and vibrating sample magnetometer techniques. For II and III it is necessary to include the effects of spin wave energy renormalization, with temperature, to account for the variation of M over a comparable temperature regime. That is, the parameter B obeys the relation: B(T) =B0[1/(1−&agr;T5/2)]3/2. In terms of the spin wave stiffness this implies D=D0[1−&bgr; (T/Tc)5/2] meV‐A˚2where, again, the parameter values are in the range found for similar systems by neutron scattering.

ISSN:0021-8979    

DOI:10.1063/1.327262

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Magnetic inelastic neutron scattering studies have been performed on ribbon specimens of amorphous Fe83B16.5Si0.5and Fe20Ni60B19P1. The samples were prepared from isotopically enriched B to reduce the neutron absorption. The Curie temperatures for the two materials are 613 K and 410 K respectively, and the room temperature saturation magnetizations 4&pgr;Msare 16.0 kG and 5.1 kG. In the Fe20Ni60B19P1specimen, well‐defined spin waves were observed at room temperature for neutron wave‐vector transfers in the range q=0.06 A˚−1to q=0.20 A˚−1. After correcting for instrumental resolution, the data obeyed a quadratic dispersion law with spin stiffness D=80 meV‐A˚2. Spin waves in the Fe83B16.5Si0.5amorphous alloy exhibited a D=125 meV‐A˚2consistent with the higher Tcof this alloy.

ISSN:0021-8979    

DOI:10.1063/1.327248

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

By using a chill‐casting technique, binary Co100−xBxalloys have been made for the boron content x between 10 and 31. The alloys with 14 ?x?29 are found to be noncrystalline, others being partially crystalline. The saturation magnetic moment per Co atom varies linearly from 1.49 &mgr;Bat x=14 to 0.98 &mgr;Bat x=29. At x=25, we find &mgr;s=1.09 &mgr;Bwhich is close to &mgr;s=1.11 &mgr;Bfor the crystalline Co3B. The ferromagnetic Curie temperature, &Vthgr;f, is above the crystallization temperature of the material for x < 27 and is estimated to vary from about 780 K for x=22 to 670 K for x=29, giving a value of &Vthgr;f= 725 K for x=25. This value is close to &Vthgr;f= 747 K for the crystalline Co3B. Other evidence is given that the magnetic properties of glassy Co‐B alloys differ very little from those of the crystalline counterparts, being quite different from the glassy Fe‐B case reported previously.

ISSN:0021-8979    

DOI:10.1063/1.327249

出版商:AIP    

年代:1979

数据来源: AIP