Al

8

B

4

C

7

was synthesized by using borax

aluminum and carbon powders as the starting materials and adding different amount of K

2

O. The powders were fully mixed and then pressed into cylindrical samples with the size of 20 mm×20 mm at 200 MPa. The samples were dried and heated at different temperatures in the flowing argon atmosphere. The effect of K

2

O content and the sintering temperature on the phase composi

tion and microstructure of Al

8

B

4

C

7

was investigated by the chemical analysis

XRD and SEM methods. The results show that in the synthesis process of Al

8

B

4

C

7

the K

2

O content in the sintered samples was 0.019%-0.028%

and no new phase containing K element was detected although the K

2

O content in the starting materials was different. K

2

O enhanced the formation temperature of Al

8

B

4

C

7

from 1 300 ℃ to 1 400 ℃ and K

2

O significantly reduced the generation of Al

8

B

4

C

7

at 1 700 ℃. In addition

Al

8

B

4

C

7

particles showed irregular shape with the size of ～1 μm after K

2

O was added to the starting materials.