110 Prakt. Met. Sonderband 47 (2015) 
successfully prevented the oxidation of the rare-earth (RE) elements. The RE's are extremely 
susceptible to oxidation, thus high vacuum and high purity protective gases are a necessity for 
obtaining alloys of high quality (table 5). | 
Table 3. ICP-OES measurements results 
oo Dy Fe. Nd Pr B Ga Al Cu Co 
 (wt%)  (Wt%)  (Wt%)  (WtY%)  (Wt%) (wt%)  (Wt%)  (WtY%)  (Wt%) 
Target composition 3,60 64,00 27,40 0,60 0,93 0,20 0,15 0,15 3,00 
Sample 1 3.67 61,56 29,18 0,61 0,99 0,22 0,25 0,26 3,25 
Sample 2 3,38 63,46 27,90 0,66 1,03 0,18 0,20 0,19 2,99 
Sample 3 3,38 63,36 27,97 0,65 1,06 0,19 0,22 0,21 2,96 ol 
210 rom 240 rpm 
Mees 
foe 
RPK 
. Ju um SU ur : 
280 rom 
Fig. 1: Optical micrographs of the polished cross section showing the microstructure of the NdFeB flakes at different 
wheel speeds 
In centrifugal atomization technique by varying the parameters of the device, the flakes can be 
produced with different thicknesses. It was observed that the increase in the wheel speed from 210 
rpm to 280 rpm results in a decrease in the flakes thickness from ~320 to ~120 um. As the increase 
in the wheel speed leads to a reduced flakes thickness, the cooling rate increases, and therefore the 
microstructure gets finer. Moreover, with increasing wheel speed changes also the mode of 
solidification for equiaxed to directional (fig. 1 a.b.c and fig. 2a and fig. 3a). Which leads to