Table 2.

The low magnification judgment results.

Content	Central Segregation	Center Porosity
0 Ce	B 1.0	1.0
0.0006 wt.% Ce	B 1.0	1.0
0.0009 wt.% Ce	C 1.0	1.0
0.0013 wt.% Ce	B 1.0	1.0