Microstructure of NdFeB permanent magnets under directional solidification
Microstructure of NdFeB permanent magnets under directional solidification
We also provide neodymium magnet ceramic magnet, alnico magnet, SmCo magnet, rubber magnetand magnetic products. These products are widely used in micro-motor, motor, computer, instrument, meter, automobile, motorcycle, horologe, office equipment, toy, magnetic therapy device and daily life industries.
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Peritectic solidification is one of very important phase transformations.Recently,many aspects of peritectic solidification have been investigated mainly on alloys which grow in non-small plane style,such as Fe-Ni,Ti-AI,Pb-Bi and Zn-based alloys. But phases formed morer frequently in a peritectic reaction are intermetallic ones, which have faceted plane,such as Nd2Fe14B phase of NdFeB alloys and 123 phase of Y-Ba-Cu-O alloys.A study of solidification structure for NdFeB alloys is helpful to understand peritectic solidification theory and to improve the property of materials.
In this thesis,the solidification microstructures of hypoperitectic composition stoichiometic and hypeperitectic composition NdFeB alloys are research at the withdraw velocity ranging form 5um/s to 500um/s under directional solidification.
The results indicate that the final microstructures in the composition of hypoperitectic alloys are primary a-Fe phase,Nd2Fel4B phase.For stoichiometic and hyperperitectic composition alloys,they are a-Fe phase,Nd2Fe14B phase and Nd-rich phase,respectively.With increasing withdraw velocity primary dendrite arm spacing of primary a-Fe phase decreases,the volume fraction of primary a-Fe phase decreases and then increases,Nd2Fe14B phase increases and then decreases.
The solidification microstureture of hyperperitectic composition NdFeB alloys are also researched at the scan rates ranging from 1500mm/min to 6500mm/min by laser surface remelting.
The results show that there are some remaining a-Fe dendrites at the bottom of molten pool,their primary dendrite arm spacings range from 100 um to 101um. Nd2Fe14B phase grow in dendrite as primary phase because of high cooling rate.they grow directionally at the bottom of molten pool,with increasing distance form bottom, the directional growing are partial.There are dendrites at the top of the molten pool,their primary dendrite arm spacing range is 10 0um.
We also provide neodymium magnet ceramic magnet, alnico magnet, SmCo magnet, rubber magnetand magnetic products. These products are widely used in micro-motor, motor, computer, instrument, meter, automobile, motorcycle, horologe, office equipment, toy, magnetic therapy device and daily life industries.
Xiamen Everbeen Magnet Electron Co.,Ltd. http://www.china-magnet.net
Add:Unit H, 4F Rihua Mansion, No. 8 Xinfeng 2nd road, Torch Hi-Tech Zone, Xiamen, China.
Tel:0086-592-5781916
Fax:0086-592-5123653
E-mail:info@china-magnet.net
Tags: neodymium magnets NdFeB permanent magnets Smco magnets