Abstract
To decrease the temperature coefficients of sintered Nd-Fe-B magnets, the influencing factors on temperature coefficients, especially the reversible temperature coefficient ? of intrinsic coercivity Hcj, were analyzed. The results showed that the absolute value of ? decreased with increasing Hcj and also the ratio of microstructure parameter c to Neff, indicating that the increase of magnetocrystalline anisotropy field HA and c/Neff can effectively decrease the absolute value of ?. On the basis of this analysis, a sintered Nd-Fe-B magnet with a low temperature coefficient of Hcj was fabricated through composition design, and the value of ? was only -0.385%/?C in the temperature interval of 20-150?C.
Highlights
Due to remarkable magnetic properties, sintered Nd-Fe-B magnets have been used extensively
In order to overcome the deficiency of Nd-Fe-B magnets, besides the higher coercivity, the lower irreversible temperature coefficients of intrinsic coercivity Hcj and remanence Jr and Br, corresponding to β and α respectively, are both essential, especially the former one
Previous reports have shown that the substitution of heavy rare-earth element Dy for Nd effectively decreases the absolute value of β, because of the increase of anisotropy field HA and Hcj [2, 3]
Summary
Due to remarkable magnetic properties, sintered Nd-Fe-B magnets have been used extensively. Previous reports have shown that the substitution of heavy rare-earth element Dy for Nd effectively decreases the absolute value of β, because of the increase of anisotropy field HA and Hcj [2, 3]. Another method is to add structure-modifying elements, such as Al, Cu, Ga, Nb, Zr, Ti, V and Mo etc [4,5,6,7]. ΒHA and αJs are the reversible temperature coefficient of anisotropy field and saturation magnetic polarization of Nd2Fe14B, with the value of approximately -0.24 % and -0.13 % at 25-150oC [13], respectively. The higher HA and c/Neff result in the lower β
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