Effect of Mn Additions on the Microstructure of Nd₉Fe_85－xB₆Mn_x Nanocomposite

Abstract: The long-rang and local structures of the Nd₉Fe_85－xB₆Mn_x(x=0.5,1.0)nanocomposite produced at melt spinning speed of 20m/s have been investigated by X-ray absorption fine structure(XAFS) and X-ray diffraction (XRD).The crystallized samples were annealed at temperatures 700°C for 5 minutes with a high heating rate.The results show that in the initial samples,the structures of the Nd₉Fe_85－xB₆Mn_x manocomposite were strongly correlated with the addition of Mn atoms.Following the increase of Mn content,the long-range and local orders of the Nd₉Fe_85－xB₆Mn_x nanocomposite increase,and a soft magnetic phase of α-Fe and a hard magnetic phase of Nd₂Fe₁₄B were formed at the addition of 1% Mn.However,the addition of element Mn can not lead to the generation of new phases or the deeper crystallization for the Nd₉Fe_85－xB₆Mn_x nanocomposite.We consider that during the preparation,element Mn was alloyed into the main lattice of the Nd₉Fe_85－xB₆Mn_x nanocomposite with a metastable structure; through annealing,the Mn atoms were separated from the initial main lattice to the borders of crystalline grain.