非晶Nd_3Fe_(81)B_(16)合金的晶化及其对磁性和Mssbauer谱的影响

CRYSTALLIZATION OF AMORPHOUS Nd Fe_(81)B_(16) ALLOYS AND ITS INFLUENCE ON MAGNETIC PROPERTIES AND MSSBAUER SPECTRA

本文报道利用单辊方法制备的非晶Nd_3Fe_(81)B_(16)合金的晶化及其对磁性和Mossbauer谱的影响。发现在非晶Fe_(81)B_(19)合金中用3at％Nd取代B,使非晶Fe_(81)B_(19)合金的晶化温度提高88℃。在适当的退火条件下晶化后样品在室温下的磁性是:σ_2=189emu/g,σ_r/σ_5=0.7,_iH_c=2.15kOe,B_r≈12kG,_bH_c=2kOe,(BH)_(max)≈8MGOe。与目前广泛使用的六角铁氧体相比,_bH_c相近,但B_r和(BH)_(max)远比六角铁氧体高。这种材料仅含有少量的Nd,因此可能开发为一种新的廉价永磁材料。本文对少量Nd的添加对非晶FeB合金的晶化温度,磁性和Mossbauer谱的影响进行了讨论。初步探讨了高矫顽力的来源,认为它的磁化和反磁化过程可以用畴壁钉扎理论解释。

Crystallization and its influence on magnetic properties and Mossbauer spectra in the rapidly solidified amorphous Nd_3Fe_(81)B_(16) alloys are reported. The addition of 3at% Nd to FeB alloys raises the crystallization temperature from 435℃ for Fe_(81)B_(19) to 523℃ for Nd3Fe_(81)B_(16). After the crystallization at the optimal annealing condition the magnetic properties as permanent magnet were obtained to be: B_r≈12kG, bH_c = 2 kOe, and (BH)max≈8 MGOe, with room temperature seturation magnetization σ_s = 189 emu/g, remanence ratio σ_s/σ_s = 0.7 and intrinsic coercivity iHC = 2.15kOe. Comparing with widely used anisotropic BaFe_(12)O_(19) ferrite, its B, and (BH)_(max) is much higher. Therefore this material may be developed into a new cheap pe manent magnet. The influence of small addition of Nd on the physical properties of the alloys-are discussed. Based on the data from X-ray diffraction, Mossbauer spectrocopy, SEM and magnetic measurments, the mechanism controlling the magnetization and demagnetization processes is thought to be domain wall pinning.