ZrB2-ZrCxN1−x Eutectic Composites Produced by Melt Solidification

Ceramic eutectics are naturally occurring in‐situ composites and can offer superior mechanical properties. Here, ZrB2–ZrCxN1−x quasi‐binary ceramic eutectic composites were produced by arc‐melting a mixture of ZrB2, ZrC, and ZrN powders in an N2 atmosphere. The arc‐melted ZrB2–ZrCxN1−x composites containing 50 mol% of ZrB2 (irrespective of the ZrC/ZrN ratio) showed rod‐like eutectic structures, where ZrCxN1−x single‐crystalline rods were dispersed in the ZrB2 single‐crystalline matrices. Multiple orientation relationships between the ZrCxN1−x rods and the ZrB2 matrices were observed, and one was determined as ZrB2 { 01 1 ¯ 0 } //ZrxN1−x {111} and ZrB2 < 2 1 ¯ 1 ¯ 0 > //ZrCxN1−x < 10 1 ¯ > . The rod‐like eutectic composites had higher hardness than the hypo‐ and hypereutectic composites and the 50ZrB2–40ZrC–10ZrN (mol%) eutectic composite showed the highest Vickers hardness (Hv) of 19 GPa.