514 Prakt. Met. Sonderband 38 (2006) 
powder by attrition milling for 30 min, 150 min. and 270 min., respectively. It can be seen 
that the particle of the mixed powder (b) becomes smaller in size than (a) powder. Many 
granular type and platelike Y123 grains with the small additives are observed with a size of 
1-20 in powder (a) while finer and more edged particles with about 10 or less in size are 
observed in powder (b). As the attrition milling time further increased from 30 min. to 150 
min, the size of the individual particles reduced to 0.2~0.30, while larger particles in size 
with 0.50 or more also exist. In the case of the particles with 270 min. attrition milling, the 
particles reached to 0.10 or less in size and strongly agglomerated as shown in (d). 
i th 
{c (cl 
Fig. 2: SEM micrographs of the attrition milled Y123 precursor powder for 
(a) as calcined, (b) 30min. (c) 150min. (d)270min. 
3.2 Distribution of the second phase particles in the melt-textured Y123 matrix 
3.2.1 Variation of BaCeOj; contents 
The segregation of the Y211 and BaCeO; within the Y123 domain was examined in the 
Y123 sample melt-textured with various amounts of BaCeO; addition from 0 wt.% to 20 
wt.%. Figure 3 shows the microstructures of the Y123 sample melt-textured with (a) no 
addition, (b) 5 wt.%, (c) 10 wt.%, and (d) 20 wt.% BaCeOj3 addition. Many microcracks due 
to the phase change are observed in Y123 phase in sample (a), while the microstructure 
(b)-(d) showed more homogeneous distribution of fine trapped particles in Y123. It is also 
found that microcracks are remarkably reduced. As the content of the BaCeO- increased.