https://www.tcd.ie/Physics/people/Graham.Cross/SF%20Poster%202011/Inoue-ActaMater00-Stabilization%20of%20metallic%20supercooled%20liquid%20and%20bulk%20amorphous%20alloys.pdf

Stabilization of metallic supercooled liquid and bulk amorphous alloys

Physical metallurgy of Ti–Ni-based shape memory alloys

Metal hydride materials for solid hydrogen storage: a review

In this chapter, we will restrict our attention to the ferrites and a few other closely related materials. The great interest in ferrites stems from their unique combination of a spontaneous magnetization and a high electrical resistivity. The observed magnetization results from the difference in the magnetizations of two non-equivalent sub-lattices of the magnetic ions in the crystal structure. Materials of this type should strictly be designated as “ferrimagnetic” and in some respects are more closely related to anti-ferromagnetic substances than they are to ferromagnetics in which the magnetization results from the parallel alignment of all the magnetic moments present. We shall not adhere to this special nomenclature except to emphasize effects, which are due to the existence of the sub-lattices.

Ferromagnetic materials

https://www.andrew.cmu.edu/user/dl0p/laughlin/pdf/PMS.pdf

Amorphous and nanocrystalline materials for applications as soft magnets

This paper reviews our results on the development of a new type of soft magnetic material with high saturation magnetic flux density (Bs) above 1.5 T as well as excellent soft magnetic properties. A mostly single bcc structure composed of α-Fe grains with about 10–20 nm in size surrounded by a small amount of an intergranular amorphous layer was obtained by crystallization of amorphous alloys prepared by melt-spinning technique. The typical nanocrystalline bcc Fe 90 Zr 7 B 3 , Fe 89 Hf 7 B 4 and Fe 84 Nb 7 B 9 ternary alloys subjected to the optimum annealing exhibit high Bs above 1.5 T as well as high effective permeability (μe) at 1 kHz above 20000. Excellent soft magnetic properties of the nanocrystalline Fe-M-B based alloys can be obtained by the decrease in the bcc grain size, magnetostriction (λ) and the increase in Tc of the intergranular amorphous phase by optimizing the crystallization process, chemical composition and adding small amounts of elements. For example, the improved FeZrNbBCu alloy shows the high ue of 160000 combined with the high Bs of 1,57 T. This excellent μe is comparable to those of nanocrystalline Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 and the zero-magnetostrictive Co based amorphous alloys, and the high Bs is comparable to those of the Fe based amorphous alloys with rather good soft magnetic properties. The excellent characteristics of a power transformer, a common mode choke coil, a pulse-transformer and a flux gate magnetic detector made of ‘NANOPERM ™ ’ were found in agreement with its very low core losses, sufficient thermal stability and low stress-sensibility of magnetic properties. The nanocrystalline Fe-M-B based alloys ‘NANOPERM ™ ’ is therefore expected to be used for many kinds of magnetic parts and devices.

Nanocrystalline soft magnetic Fe-M-B (M = Zr, Hf, Nb) alloys and their applications

Crystallization from the supercooled liquid region was examined for an amorphous Zr65Al7.5Cu27.5 alloy with a significant supercooled liquid region before crystallization, with the aim of investigating the reason for the appearance of the wide supercooled liquid region. The crystallization takes place through the precipitation of a b.c.t. Zr2(Cu, Al) single phase which grows with a dendritic mode. The Avrami exponent (n value) and the activation energies for the nucleation and crystallization are 3.7, 260 and 230 kJ mol−1 respectively. Based on existing structural data as well as the present results, it is presumed that the appearance of the supercooled liquid region is due to the difficulty of growth resulting from the necessity of long-range redistribution of Al at the solid-liquid interface and to the difficulty of precipitation of Zr2(Cu, Al) caused by the large solid-liquid interfacial energy resulting from the highly dense random packed structure consisting of elements with significantly different atomic sizes and attractive bonding nature.

Stability and transformation to crystalline phases of amorphous ZrAlCu alloys with significant supercooled liquid region

A study was made of the properties and structure of Co-Zr-O nano-granular films prepared by rf reactive sputtering in an atmosphere of argon and oxygen gases. We found soft magnetic Co-Zr-O films in a wide compositional range near Co-ZrO/sub 2/ and investigated systematically the compositional dependence of their magnetic properties and electrical resistivity. The films near Co/sub 60/Zr/sub 10/O/sub 30/ simultaneously have anisotropy fields more than 150 Oe, coercivities less than 3 Oe, saturation magnetizations more than 9 kG, and electrical resistivities more than 1000 /spl mu//spl Omega/cm. The frequency response of permeability of these films is excellent. And they show a high resonance frequency exceeding 3 GHz.

Co-Zr-O nano-granular thin films with improved high frequency soft magnetic properties

Effect of ball milling on hydrogen absorption properties of FeTi, Mg2Ni and LaNi5

This paper reviews our recent results on some applications of new nanocrystalline soft magnetic Fe-M-B (M=Zr, Hf, Nb) alloy ribbons "NANOPERM(R)". NANOPERM(R) has a structure consisting of nanoscale bcc grains and a small amount of an intergranular amorphous layer. NANOPERM(R) exhibits high saturation magnetic flux density above 1.5 T as well as excellent soft magnetic properties. Furthermore, its remanence ratio can be controlled according to the demands of various applications. Toroidal cores with gap, common mode choke coils, ISDN (integrated service digital network) interface pulse transformers and flux gate magnetic detectors made of "NANOPERM(R) have been developed. The excellent characteristics of the components were confirmed in trial. NANOPERM(R) is therefore expected to be used widely in the magnetic application field.

T. Masumoto

Papers

Nanocrystalline soft magnetic Fe-M-B (M = Zr, Hf, Nb) alloys and their applications

Stability and transformation to crystalline phases of amorphous ZrAlCu alloys with significant supercooled liquid region

Co-Zr-O nano-granular thin films with improved high frequency soft magnetic properties

Effect of ball milling on hydrogen absorption properties of FeTi, Mg2Ni and LaNi5

Applications of nanocrystalline soft magnetic Fe-M-B (M=Zr, Nb) alloys "NANOPERM(R)"