Microstructural study of hot pressed HDDR Nd - Fe - B magnets

Estévez, E.; Fidler, J.; Short, C.; Harris, I.R.

doi:10.1088/0022-3727/29/4/002

Cited by 8 publications

(5 citation statements)

References 8 publications

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“…From viewpoint of transformation kinetics there is explanation of processes of abnormal growth of Nd 2 Fe 14 B hard magnetic phase. As it has been shown in our previous works [20][21][22][23] [25,34,35].…”

Section: Resultsmentioning

confidence: 56%

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Nanocrystalline microstructure formation during hydrogen-induced phase transformations in Nd2Fe14B hard magnetic alloy

Rybalka¹

2012

LoM

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Донецкий национальный технический университет, ул. Артема 58, 83000 Донецк, Украина The kinetics and features of nanocrystalline microstructure formation during direct and reverse hydrogen-induced phase transformations in Nd 2 Fe 14 B alloy has been studied. It has been established that a hydrogen-vacuum treatment carried out in accordance with the kinetic data of transformations in Nd 2 Fe 14 alloy leads to a formation of nanocrystalline homogeneous microstructure with average grains size ~0.3 μm. It is shown that carrying out direct and reverse transformations taking into account of kinetic features of transformations as temperature and transformation time allow to avoid abnormal growth processes a main hard magnetic Nd 2 Fe 14 B phase that is one of the main factors for permanent magnets obtaining with high coercivity without very complicated and expensive of alloying procedures.

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Section: Resultsmentioning

confidence: 56%

“…However, as an example, in some cases when some above-described HDDR schemes were applied to Nd 2 Fe 14 B type alloys with various chemical composition it can lead to the abnormal grains growth processes of a hard magnetic Nd 2 Fe 14 B F-phase up to tens-hundreds mm [25,34,35] and coercivity decrease.…”

Section: Resultsmentioning

confidence: 99%

Nanocrystalline microstructure formation during hydrogen-induced phase transformations in Nd2Fe14B hard magnetic alloy

Rybalka¹

2012

LoM

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“…Consequently, obtained microstructure should consist from many numbers of Nd 2 Fe 14 B grains with small sizes and with not numerous large Nd 2 Fe 14 B grains. Really, the above-described microstructure was observed experimentally in some Nd 2 Fe 14 B type alloys during HDDR-treatment [9,23,24].…”

Section: Kinetics and Microstructure Inmentioning

confidence: 91%

“…In some cases when some abovedescribed HDDR schemes were applied to Nd 2 Fe 14 B type alloys with various chemical composition it can lead to the abnormal grains growth processes of a hard magnetic Nd 2 Fe 14 B -phase up to tens-hundreds m [23,24] and coercivity decrease.…”

Section: Introductionmentioning

confidence: 99%

Some kinetic and microstructural aspects during hydrogen-induced phase transformations in alloys

Rybalka

Dodonova

Didus

2005

Journal of Alloys and Compounds

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“…Such materials are characterized by very good magnetic properties such as low coercivity or high saturation magnetization [37][38][39].Alloys of this kind can be achieved in several ways. There are known methods such as chemical methods of vapor deposition, sonochemistr y), spraying methods, mechanical synthesis or hydration methods [40][41][42][43][44][45][46]. Often nanocrystalline materials are obtained using rapid cooling.…”

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confidence: 99%

Effect of Annealing on the Curie Temperature in the Bulk Amorphous Alloys

Jeż¹

2017

Rev. Chim.

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The paper presents results of research for volumetric amorphous alloys Fe 61+x Co 10-X Y 8 W 1 B 20 where x = 0,12 in the shape of plater of 10mm x 5mm x 0.5mm diameter. Amorphous Samales were annealed at 953K for 10 minutes what caused their partial crystallization. As a result of the thermal interference in the volume of alloys, three different crystalline phases were formed aFe, Fe 5 Y and Fe 3 B. For samples after solidification and after thermal treatment thermomagnetic studiem were conducted. For amorphous alloys, only one ferroparamagnetic transition was visible, and for the alloys after the isothermal annealing process there were two inflections on the curve .µ 0 M s (T) corresponding to the two Curie temperatures. These intersections came from two amorphous phases. As a result of the research, it was found that these alloys crystallized in the primal crystalization. Crystallization was the reason for the increase of the first Curie temperature of the amorphous matrix while retaining its decrease with cobalt additive. The value of the second Curie temperature in the alloys after heating was found to depend mainly on the size of the crystallization products and in particular on the Fe 5 Y crystallite size.Conventional polycrystalline alloys are one of the most widespread materials in the world. Structures of countless grades of steel or aluminum are virtually impossible to replace by any other materials. On a macroscopic scale, the cost of materials is extremely important. Production of quality materials in conventional form is very well controlled and relatively cheap, even in the case of metal composite materials [1][2][3][4]. By moving from macroscopic engineering applications to precise and specialized products, production costs become less and less important, and more and more roles take over the properties of the materials produced. In many industries, emphasis is placed on selected properties. Magnetic properties are extremely important for different applications. At this point, polycrystalline materials often do not have satisfactory properties In this field. The answer to the search for materials that meet the high demands on the magnetic properties of alloys are rapid cooled materials [1,[5][6][7][8][9][10]. Despite the identical chemical composition, these materials have completely different properties than their crystalline counterparts. Research on this type of material has been going on for several decades. The beginnings of quick-cooled alloys were not impressive. Despite the good magnetic properties, the problem was the form of material obtained. The first alloys for which an amorphous structure was obtained were made in the form of tapes of thicknesses of around 50 µm. The liquid melt casting method on the rotating cylinder allows very high cooling rates (10 5 -10 6 K/s) what gives a very good chance of obtaining an amorphous structure for many chemical compositions [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Unfortunately, this small dimension drastically limited the abi...

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Microstructural study of hot pressed HDDR Nd - Fe - B magnets

Cited by 8 publications

References 8 publications

Nanocrystalline microstructure formation during hydrogen-induced phase transformations in Nd2Fe14B hard magnetic alloy

Nanocrystalline microstructure formation during hydrogen-induced phase transformations in Nd2Fe14B hard magnetic alloy

Some kinetic and microstructural aspects during hydrogen-induced phase transformations in alloys

Effect of Annealing on the Curie Temperature in the Bulk Amorphous Alloys

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