The effects of Co on the enhancement of magnetic properties by modifying the intergranular phase in Nd-Fe-B alloys

Powder metallurgical additions of Bi enhance the temperature stability of (Nd, Dy)-Fe-B permanent magnets. Bi is not solved in the hardmagnetic RE2Fe14B phase, thus does not influence the intrinsic magnetic properties, Only the microstructure of the sintered magnets is changed. Addition of a few wt.% of Bi leads to the formation of a new ternary intergranular phase with the composition Nd6Fe13Bi. This phase substitutes partially the intergranular Nd-rich phase providing the magnetic insulation of hardmagnetic grains. An enhancement of HCJ by about 40% was reached at 150 ºC for a Nd15.5Dy1.5Fe74AlB8 magnet containing 2.5 wt.% Bi compared to the Bi-free material.

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Temperature dependence of post-sintered annealing on magnetic properties of intergranular phase in Nd-Fe-B permanent magnet

Journal of Applied Physics ◽

10.1063/1.4916938 ◽

2015 ◽

Vol 117 (17) ◽

pp. 17B313 ◽

Cited By ~ 7

Author(s):

Akira Yasui ◽

Tetsuya Nakamura ◽

Yoshinori Kotani ◽

Tomoki Fukagawa ◽

Takeshi Nishiuchi ◽

...

Keyword(s):

Magnetic Properties ◽

Temperature Dependence ◽

Permanent Magnet ◽

Intergranular Phase

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AEM analysis of crystallization in Ti-based amorphous alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075142 ◽

1983 ◽

Vol 41 ◽

pp. 270-271

Author(s):

A.R. Pelton ◽

A.F. Marshall ◽

Y.S. Lee

Keyword(s):

Magnetic Properties ◽

Amorphous Alloys ◽

Amorphous Materials ◽

Isothermal Annealing ◽

Amorphous Matrix ◽

Nucleation And Growth ◽

Current Interest ◽

Amorphous Films ◽

Electrical And Magnetic Properties

Amorphous materials are of current interest due to their desirable mechanical, electrical and magnetic properties. Furthermore, crystallizing amorphous alloys provides an avenue for discerning sequential and competitive phases thus allowing access to otherwise inaccessible crystalline structures. Previous studies have shown the benefits of using AEM to determine crystal structures and compositions of partially crystallized alloys. The present paper will discuss the AEM characterization of crystallized Cu-Ti and Ni-Ti amorphous films.Cu60Ti40: The amorphous alloy Cu60Ti40, when continuously heated, forms a simple intermediate, macrocrystalline phase which then transforms to the ordered, equilibrium Cu3Ti2 phase. However, contrary to what one would expect from kinetic considerations, isothermal annealing below the isochronal crystallization temperature results in direct nucleation and growth of Cu3Ti2 from the amorphous matrix.

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Microstructure in soft magnetic E3 (S1, Al) (Sendust) alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105916 ◽

1988 ◽

Vol 46 ◽

pp. 770-771

Author(s):

June D. Kim

Keyword(s):

Electron Microscopy ◽

Magnetic Properties ◽

Ternary Phase Diagram ◽

Vertical Tube ◽

Vacuum Induction Melting ◽

Induction Melting ◽

Soft Magnetic ◽

Quenching Temperature ◽

Thin Foils ◽

Vertical Tube Furnace

Iron-base alloys containing 8-11 wt.% Si, 4-8 wt.% Al, known as “Sendust” alloys, show excellent soft magnetic properties. These magnetic properties are strongly dependent on heat treatment conditions, especially on the quenching temperature following annealing. But little has been known about the microstructure and the Fe-Si-Al ternary phase diagram has not been established. In the present investigation, transmission electron microscopy (TEM) has been used to study the microstructure in a Sendust alloy as a function of temperature.An Fe-9.34 wt.% Si-5.34 wt.% Al (approximately Fe3Si0.6Al0.4) alloy was prepared by vacuum induction melting, and homogenized at 1,200°C for 5 hrs. Specimens were heat-treated in a vertical tube furnace in air, and the temperature was controlled to an accuracy of ±2°C. Thin foils for TEM observation were prepared by jet polishing using a mixture of perchloric acid 15% and acetic acid 85% at 10V and ∼13°C. Electron microscopy was performed using a Philips EM 301 microscope.

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