Study on microstructure optimization and properties of sintered NdFeB permanent magnetic materials
Time:05/11/2011
Study on microstructure optimization and properties of sintered NdFeB permanent magnetic materials
Sintered NdFeB magnet is a new generation of rare earth permanent magnetic material with outstanding
magnetic properties and high cost performance,and has been applied widely in various hi tech fields.However,the disadvantages of low coercivity,poor thermal stability,and easy corrosion seriously restrict its further development and application.In addition to the magnet composition,microstructure is also an important factor influencing the properties of sintered Nd-Fe-B magnets.Therefore,how to improve its overall properties through adjusting
Microstructure of the magnet is of both theoretical and practical significance.
In this dissertation,aiming to adjust and modify the microstructure of sintered Nd-Fe-B materials,the effects of intergranular phase modification on the magnetic properties,corrosion resistance and thermal stability were systematically investigated.An ideal distribution model of
Nano-sized additives on the surface of magnetic powders was proposed.Several possible
Influencing mechanisms of different nano-sized additives on grain size and distribution of the
Main phase Nd2Fel4B,on the interface structure of main phase/Nd-rich phase,and on the
Properties of magnet were revealed on the basis of thermodynamic calculation.Meanwhile,the
Variation law of the properties and microstructure of magnet with additive content of ultrafine
Powders were made clear by intergranular addition.Furthermore,through investigating the
Variation of temperature coefficient with intrinsic property and microstructral parameter,the
Design principle of sintered Nd-Fe-B magnets with high thermal stability was suggested,and the
Magnet with low temperature coefficient was successfully prepared.