Preparation of rare earth - transition metal (RE: Y, Tm: Co) intermetallic compounds by calciothermic reduction diffusion process

Ilayaraja, M.; Berchmans, L. John; Sankaranarayanan, S. Raman

doi:10.5937/metmateng1401035i

Cited by 7 publications

(7 citation statements)

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“…The Nb 3 Sn superconducting phase powder is obtained by Ca or Mg vapor reduction from a mixture of Nb 2 O 5 and SnO 2 or NbCl 5 and SnCl 2 •H 2 O powders. The powder has -Reduction by the CRD method [25] Measured are some magnetic properties Reduction by the CRD method [28] Bulk density 3.45-3.55 g/cm 3 , fluidity 30-40 s Calcium hydride method [4, 19, 80-…”

Section: Niobium-tin Systemmentioning

confidence: 99%

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Calciothermic powders of rare metals and intermetallic compounds

Kasimtsev¹,

Yudin²,

Levinsky³

2020

nfm

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This paper presents a profound review of scientific and technical literature on the issues of calciothermic production of powders of rare metals, intermetallic compounds, composite materials and refractory oxygen-free compounds (carbides, nitrides). Calciothermic reduction is a metallothermic synthesis method for those substances where calcium or its derivatives, such as calcium hydride or calcium carbide, are used as a reducing agent. Thermodynamics aspects of a reduction process are covered in the paper broadly, with particular emphasis on assessing the reduction depth of original oxide raw materials, as TiO2. The mechanism and kinetics of calciothermic synthesis of single-component and multi-component alloys are described. Presented are both technological means of obtaining materials and hardware resources of many varieties of calciothermic method. The key features of the work are generalization and systematization of properties (chemical, physical, technological) of materials synthesized by calciothermic method. The data are accumulated in the appropriate tables and divided by substance classes (powders of metals and alloys, powders of intermetallic compounds, powders of carbides, powders of nitrides, and powders of composite materials). Methods of calciothermic powder making in case of the singlecomponent and complex multi-component systems are briefly described. This work will be interesting to the students of metallurgical profile and specialists whose scientific interests are in the field of material synthesis by methods of powder metallurgy.

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Section: Niobium-tin Systemmentioning

confidence: 99%

“…The method is used mainly for the production of powders of alloys and intermetallic compounds. In the Ca melt, there are particles of oxides of the reduced metal, whose atoms diffuse from the melt to the alloying element particles, then they diffuse into alloys or intermetallic compounds [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

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confidence: 99%

Calciothermic powders of rare metals and intermetallic compounds

Kasimtsev¹,

Yudin²,

Levinsky³

2020

nfm

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“…The free energy change of reaction at 1223 K, 1273 K and 1323 K could be calculated as [4], ΔG =ΔGº 298(1) + RT ln K (15) ΔG T = -104744.8-154.9 T + RT ln (P ca / Pº) -3…”

Section: Thermodynamics Of the Systemmentioning

confidence: 99%

“…Several other useful modifications of calciothermic reduction have been successfully developed for the preparation of this neodymium-bearing magnetic alloy [3]. The Y-Co alloy system has been studied and reported earlier [4]. The presence of rare-earth metals in magnet alloys has a surprising influence on magnetic properties, and hence the measurement of magnetic properties is much important, in the context of developing new magnetic materials.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Y- Ni alloy by calciothermic reduction diffusion process

Ilayaraja¹,

Berchmans

Sankaranarayanan³

2015

Metall Mater Eng

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In this study, magnetic material of the Yttrium based alloy such as nickel intermetallic compound is prepared by calciothermic reduction process (CRD), at different temperatures, for 7 hours, under Argon atmosphere. Kinetic analyses have been used to calculate the conversion rate and the rate constant at different temperatures. Thermodynamic calculations have been performed to estimate the Gibbs free energy at different temperatures. Scanning Electron Microscopy (SEM), X-ray diffraction and EDX analysis have been performed to characterize the samples produced at 1273 K. Magnetic properties have been estimated using Vibrating Sample Magnetometer.

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“…Standard reduction potential of elements[90] vital advance in synthesizing Nd-Fe-B powder is the Reduction Diffusion (RD) technique. Intensive efforts have been devoted in this research area[87,[91][92][93][94][95][96][97][98][99]. Ca has a high reduction potential of -2.87 eV (Ca 2+ →Ca, -2.87 eV).…”

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Microwave processing of Nd-Fe-Co-B magnetic materials

Tan¹

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Numerous studies have been performed in the field of Nd-Fe-B based permanent magnets since they possess excellent hard magnetic properties. The magnetic properties are closely related to the structure, phases present, processing route etc. High performance hard magnets can obtain their desired large energy product by interaction of magnetic moments at the nanoscale. Therefore, developing nanostructured Nd-Fe-B based magnets requires the study of novel synthesis techniques, microstructure and properties. Conventional physical techniques have limitations of inhomogeneity, contamination, poor control of microstructure and high cost due to the use of elemental rare earth metals. On the other hand, bottom-up chemical methods offer better control of structure at the nanoscale. The use of metal salts as precursors significantly reduces the cost. Hence, a cost-effective, bottom-up, microwave synthesis method is promising to produce homogenous particles by uniform microwave heating. The main objective of this project is the study of the microwave synthesis of Nd-Fe-B based magnets. The processing parameters, reaction mechanisms, characterization and property evaluation of these materials were carried out. Nanostructured Nd-Fe-B particles were prepared by microwave combustion and reduction diffusion. Microwave combustion resulted in a transformation from metal salts to mixed metal oxides consisting of CoFe2O4, NdFeO3, Nd3FeO6 and Fe2O3. Nd2(Fe,Co)14B nanoparticles were obtained by the reduction diffusion process, in which the mixed metal oxide was reduced by CaH2. The effects of processing parameters on properties and structure were studied. It was found that the structure and magnetic properties can be controlled by the microwave power. Higher microwave power resulted in larger grain size. The coercivity of the particles increased from ~ 6 kOe to ~9 kOe when the grain size increased from ~ 20 nm to ~ 60 nm. A range of reduction-diffusion annealing times was also tested. The highest energy product was obtained for reduction diffusion at 800 °C for 2 h. The CaO byproduct was removed by different chemicals. The optimum chemical was found to be NH4Cl (dissolved in methanol), which eliminated the use of water, thus avoiding the vigorous reaction between CaO and water.

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Preparation of rare earth - transition metal (RE: Y, Tm: Co) intermetallic compounds by calciothermic reduction diffusion process

Cited by 7 publications

References 1 publication

Calciothermic powders of rare metals and intermetallic compounds

Calciothermic powders of rare metals and intermetallic compounds

Synthesis of Y- Ni alloy by calciothermic reduction diffusion process

Microwave processing of Nd-Fe-Co-B magnetic materials

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