Title :
Segregation of W in Nd-Fe-B magnets and its effects on coercivity
Author :
Yan, Aru ; Song, Xiaoping ; Wang, Xiaotian
Author_Institution :
Inst. of Phys., Acad. Sinica, Beijing, China
fDate :
7/1/2000 12:00:00 AM
Abstract :
The coercivity of sintered Nd22Fe71B7 magnets with the combined addition of Al and W was investigated to study the role of additive elements in improving the coercivity in the NdFeB system. It was found that the coercivity could be greatly enhanced by the Al and W combined addition. Microstructural studies show that the alloying element W would preferentially segregate on the surface region of the main phase grain when added into the magnets together with Al, leading to a significant enhancement of coercivity. Further, thermodynamic analysis reveals that the segregation of W could be attributed to inhomogeneous nucleating on the surface region of the main phase grains during cooling
Keywords :
alloying additions; boron alloys; coercive force; ferromagnetic materials; iron alloys; neodymium alloys; nucleation; permanent magnets; segregation; sintering; tungsten alloys; Nd-Fe-B permanent magnet; Nd22Fe71B7:Al,W; W segregation; additive element; coercivity; inhomogeneous nucleation; microstructure; sintering; thermodynamic analysis; Alloying; Coercive force; Magnetic properties; Magnets; Microstructure; Niobium; Optical microscopy; Powders; Remanence; Scanning electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
