What is Nd-Fe-B Permanent Magnets?
Add Time:2010-02-10 15:45:19 Click:112

Nd-Fe-B(neodymium-iron-boron) material was discovered in 1983 by physicists of United StatesandJapan. It is the strongestmz made permanent magnet so far. Nd-Fe-B material is mainly a type of intermetallic compound, Nd^2FeuB, which has a compositior two rare earth atoms, 14 iron atoms and one boron atom. Besidesthe main phase Nd^2FeuB in Nd-Fe-B material, there are small amounts of rare earth-rich phase (Nd-rich phase), boron-rich phase as well as other phases. The Nd-rich phase provides pinning ~ domain walls so that Nd-Fe-B magnet has high coercive force. Today's commercial Nd-Fe-B magnets have many combinations oil partial alloying substitutions for Nd and Fe, leading to a wide range of available properties. The rare earth content of Nd-Fe-B ma alloys is typically 30 to 35 weight percent.

Today, due to its superior magnetic properties and reasonable costs, Nd-Fe-B permanent magnet has found its extensive applicat in manvfieldssuch as: computer devices, communication tools, motors, medical treatment instruments,sensors and speakers etc.

There are two families of Nd-Fe-B permanent magnets commercially available, that is, sintered and bonded magnet ^sintered Nd-l magnet is a fully densed and anisotropic material and provides the highest available magnetic energy products of any materials, ranging from 26 to so MGOe. While bonded Nd-Fe-B magnet is produced by bonding the rapidly quenched alloying powders witl polymer bonders, and shows comparably low magnetic energy products. This is mainly because the commercially available bond Nd-Fe-B magnet is isotropic on macroscopic magnetic properties and it is not a fully densed material. But isotropic bonded Nd-Fe magnet has its special advantages. For example, it can be fabricated by compression and injection molded processes and offers complex shapes with higher size-precision than sintered magnets. Moreover, unlike the anisotropic magnet that must be magnet oriented in a preferred direction during the molding process, the isotropicbonded Nd-Fe-B magnetcan be convenientlymagneti in any direction: axial, radial and multi-polar which implies complex magnetization capability over anisotropic magnets. Furtherm isotropic bonded Nd-Fe-B magnet is made from rapidly quenched powders in which particles have fine microstructures and make comparably stable in chemistry. We can also consolidate the rapidly quenched powders into a fully dense anisotropic magnet by plastic deformation to qet hiqh maqnetic enerqy products comparable with sintered maqnets.