Characterization of Directionally Solidified B_4C-TiB_2 and B_4C-SiC Eutectic Composites Prepared by Floating-Zone Method

摘要

B_4C-TiB_2 and B_4C-SiC eutectic composites were prepared by a floating zone method to modify the properties of B_4C. The B_4C-TiB_2 composites consisted of B4C matrix and rod-shaped TiB_2 where the eutectic composition was 25 mol percent TiB_2. The c-axis of B_4C matrix tilted ~20 deg from the growth direction. Twin boundaries were observed in the B_4C matrix being parallel to the growth direction and (1011) plane of B_4C. The (1011) plane of B_4C was parallel to the (0001) plane of TiB_2. The B-4C-SJC composite has a lamella structure with SiC and B_4C layers, whose eutectic composition was 53 mol percent SiC. The angle between c-axis of B_4C matrix and growth direction was about 20 deg. Twin boundaries were observed parallel to the growth direction and (111) plane of the SiC layer. The (1012) plane of B_4C was parallel to the (311) plane of SiC.