Prakt. Met. Sonderband 47 (2015) 111 
en | . . 
+ formation of columnar grains of hard magnetic Nd2Fe14B phase, surrounded by Nd- reach phase and 
; suppresses the formation of soft magnetic a-Fe phase (fig. 2 and fig. 3). 
Table 4. XRF measurements results 
Al Ge TG Dy Ye... © Gi Nd 0° Pr = SUM 
0 Go (Wt%) (Wt%) (Wt%) (Wt%) (wt%) (wt%) (wt%) (wt%) (wt%) 
7 | it io a———————————————— ———————————————————————————— —————— EEE 
; a Sample 1 0,22 3,2 0,21 3,88 61,36 0,18 29.1 0,85 99 
5 © Sample 2 0,29 3,08 0,29 3,82 63,54 0,23 27,02 0,73 99 
1 Sample 3 0,18 3,02 0,23 3,64 63,78 0,23 27.21 0,71 99 
Tabel 5. Impurities measurements on as-cast flakes 
nn © Oxygen (Wt%) © Carbon (Wt%) 
Sample 1 0,04 0,08 
Sample 2 0,029 0,06 
Sample 3 0,024 0,11 
Magnetic properties can be seen in figure 4. The magnetic properties show unambiguous 
dependency with the melting stage time (tied to dissolving of the iron in liquid phase), as well as the 
formation of the a-Fe (tied to the cooling rate and the cooling wheel speed). We can see on axis x, 
representing the remanence (Br), that the lack of iron in the alloy reduces the Br (sample 1). On the 
other hand, we can see that the increasing solidification rate, which suppresses the formation of the 
a-Fe increases the coercivity (Hcl) of the magnets. 
if QUT 
a) D) 
cn be Fig. 2: The morphology of the centrifugally atomized NdFeB flake at wheel speed of 210 rpm; SEM micrograph, 
{ from 210 polished cross section 
he increase 
wofore the