The heating of B 4 C-YTZP (where YTZP denotes yttriastabilized zirconia polycrystals) mixtures, under an argon atmosphere, generates B 4 C-ZrB 2 composites, because of a low-temperature (<1500°C) carbide-oxide reaction. Composites derived from mixtures that include >15% YTZP are better sintered than monolithic B 4 C that has been fired under the same conditions. Firing to ϳ2160°C (1 h dwell) generates specimens with a bulk density of >91% of the theoretical density (TD) for cases where the initial mixture includes >15% YTZP. Mixtures that include 30% YTZP allow a fired density of >97.5% TD to be attained. The behavior of the B 4 C-YTZP system is similar to that of the B 4 C-TiO 2 system. Dense B 4 C-ZrB 2 composites attain a hardness (Vickers) of 30 -33 GPa.

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