High energy product of isotropic bulk Sm-Co/α-Fe(Co) nanocomposite magnet with multiple hard phases and nanoscale grains

In this work, the influence of milling medium was investigated in order to achieve high energy-product Nd-Fe-B magnets, mostly by the remanence improvement related to the obtention of monocrystalline particles during milling. Nd-Fe-B alloy made by strip-casting process were used as starting material, which exhibits refined grain structure and demands special attention during milling in relation to coarse-grained, conventionally cast alloys. It was found that by using liquid medium during ball milling process, the mean particle size decreased, as well as the size distribution, which improved the particle alignment and hence the remanence in the sintered magnet. Texture was quantified by magnetic characterization based on reference isotropic magnets made in same conditions, and microstructure development was evaluated by optical microscopy. Moreover, after post-sintering treatment, the coercivity increased 20% compared to as sintered state without changing the remanence, providing an anisotropic magnet with high coercivity.

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Fe enriched Sm‐Co based high energy product sputtered films with precise crystal textures

Journal of Applied Physics ◽

10.1063/1.347846 ◽

1991 ◽

Vol 69 (8) ◽

pp. 5850-5852 ◽

Cited By ~ 4

Author(s):

H. Hegde ◽

K. Chen ◽

F. J. Cadieu

Keyword(s):

High Energy ◽

Sputtered Films ◽

Energy Product

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THE ROLE OF AMORPHOUS INTERMEDIATE PRODUCTS IN THE DEHYDRATION OF CERTAIN HYDRATED SALTS

Canadian Journal of Chemistry ◽

10.1139/v51-070 ◽

1951 ◽

Vol 29 (7) ◽

pp. 604-632 ◽

Cited By ~ 23

Author(s):

G. B. Frost ◽

K. A. Moon ◽

E. H. Tompkins

Keyword(s):

Water Vapor ◽

Vapor Pressure ◽

Zinc Sulphate ◽

Water Vapor Pressure ◽

High Vacuum ◽

High Energy ◽

Energy Liberation ◽

Heats Of Solution ◽

Energy Product ◽

Dehydration Mechanism

Following the dehydration of certain hydrated salts in high vacuum, an evolution of energy occurs. X-ray studies have shown that this energy liberation is due to an amorphous to crystalline transition in the products of dehydration. Measurements have been made of the integral heats of solution of the dehydration products of copper sulphate pentahydrate and zinc sulphate hexahydrate formed at a series of low dehydration pressures. From these measurements, the fractional amounts of relatively high energy amorphous products formed at a series of low dehydration pressures have been calculated. It has been found that as the water vapor pressure near the reaction interface is increased, the fractional amount of high energy product decreases to a minimum, then increases, passes through a maximum, followed by a slow decrease. These results are interpreted in terms of a possible dehydration mechanism, and an estimation made of the effect of water vapor pressure on the over-all reaction rate. In the course of this study, the integral heats of solution of the crystalline hydrates involved have been determined. The heats of transition of the amorphous to crystalline forms of copper and zinc sulphate monohydrates are reported.

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