Investigation of magnetic properties, after effect and MFM of PryFe90−yB10 (y=8−11.76) nanocomposites

Magnetic properties, coercivity mechanism, after effect of melt-spun PryFe90-yB10 (y = 8-11.76) nanocomposite ribbons have been investigated. Exchange coupling effect was evidenced by Henkel plot and confirmed by magnetic force images, to exist in all the ribbons if suitable crystallization treatment was employed. The optimal properties of B-r = 9.6 kG, H-i(c) = 8.3kOe and (BH)(max) = 16.2 MGOe were achieved in Pr9.5Fe80.5B10 ribbon. In addition, magnetic force microscopy studies revealed that Pr9.5Fe80.5B10 sample possessing the highest B-r showed the biggest (RMS)(Deltaphi) value (1.64degrees), confirming its strongest exchange coupling effect between grains. Furthermore, the increase of the volume fraction of magnetically soft phases with decreasing Pr concentration leads to the increment of activation volume with decreasing Pr concentration. Moreover, Pr8Fe82B10 having the lowest H-i(c) exhibited maximum values in activation volume V = 1.34 x 10(-18) cm(3), because it possessed the largest volume fraction of the magnetic soft phases, including Pr2Fe23B3, Fe3B and alpha-Fe phases. (C) 2004 Elsevier B.V. All rights reserved.