Vacuum hot pressing of Fe–Si–B–Nb-based amorphous powder cores and their high-frequency magnetic properties

AbstractComposite amorphous powder core made by field-annealing with new insulations could improve the high frequency AC magnetic and mechanical properties. All of the amorphous ribbons with composition Fe78B16Si5C and Fe40Ni38Mo4B17Si were annealed at temperature higher than their embrittlement temperature but lower than the crystallization temperature. After the ribbons become brittle, they were mechanically crushed and milled to produce powders with size about 50 ∼ 250μm. To make a core, the amorphous powders combined with insulation binder were put into an evacuted toroidal followed by hot mechanical compaction. The weight percentages of binder were about 3 wt%, 5 wt% and 10 wt%. Field-annealings were carried out for different conditions in an Ar (or N2) atmosphere chamber at elevated temperature with applied field about 10 Oe. The initial magnetization curve and saturation magnetization were measured by vibrating sample magnetometer (O≤H≤10 KOe). DC and AC magnetic properties such as permeability, coercive force, core loss, etc. were tested by B-H loop tracer. It shows the AC properties can be improved by increasing the particle size of the amorphous powder and by increasing the interparticle contacts at high frequency.

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Vacuum hot pressing of gas-atomized Ni–Zr–Ti–Si–Sn amorphous powder

Materials Science and Engineering A ◽

10.1016/j.msea.2003.11.015 ◽

2004 ◽

Vol 368 (1-2) ◽

pp. 318-322 ◽

Cited By ~ 17

Author(s):

Yoon B Kim ◽

Hyun M Park ◽

Won Y Jeung ◽

Jong S Bae

Keyword(s):

Hot Pressing ◽

Amorphous Powder ◽

Vacuum Hot Pressing

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Preparation and Magnetic Properties of Nanocrystal Bulk SmCo7 Magnets

Materials Science Forum ◽

10.4028/www.scientific.net/msf.815.276 ◽

2015 ◽

Vol 815 ◽

pp. 276-280 ◽

Cited By ~ 1

Author(s):

Qian Shen ◽

Yi Long Ma ◽

Jun Dong ◽

Deng Ming Chen

Keyword(s):

Magnetic Properties ◽

Phase Composition ◽

Ball Milling ◽

Hot Pressing ◽

Amorphous Powder ◽

High Energy ◽

High Coercivity ◽

Energy Ball ◽

Bulk Nanocrystalline ◽

Co Alloys

Two kinds of 2:17R Sm-Co alloys, Sm2(Fe,Cu,Zr,Co)17 and pure binary Sm2Co17 were prepared, and the amorphous powder was prepared by high-energy ball milling Sm-Co alloys. The bulk nanocrystalline SmCo7 was prepared by hot-pressing the amorphous powder, and the magnetic properties and phase composition were studied. Initial Sm2(Fe,Cu,Zr,Co)17 showed a large value of coercivity while the pure Sm2Co17 almost showed no coercivity. However, after ball milling the grain size of alloys decreased dramatically until completely amorphous. Two kinds of alloys showed the different phase composition and magnetic properties after hot-pressing. It was found that the pure Sm2Co17 bulk magnet showed a high coercivity Hc and had the 1:7H phase. On the other hand, the Sm2(Fe,Cu,Zr,Co)17 showed high saturation magnetization Ms and very low Hc since the Fe-Co and Sm2Co3 phase were precipitated from the alloy.

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