Phase Equilibria in the System Boron Carbide‐Silicon Carbide

The system boron carbide‐silicon carbide is quasi binary and contains a eutectic of composition 70 ± 2 wt% B 4 C and 30 ± 2 wt% Sic at a temperature of 2300°± 20° C. The solid solubility of both B 4 C in Sic and Sic in B 4 C is less than 2 wt% at this temperature, based on metallographic and X‐ray analyses. The Sic corresponds to the hexagonal (a) allotrope when the compositions contain more than 50 wt% Sic. The cubic (p) form of Sic is stabilized in compositions which contain less than 50 wt% Sic.