REACTION SYNTHESIS OF TIB2-SIC COMPOSITES FROM TIH2-SI-B4C

The phase forming mechanisms in the chemical reaction Si + 2TiH(2) + B 4C --> SiC + 2TiB(2) + 2H(2) up arrow have been investigated using the XRD technique. It was observed that TiC and Ti5Si3 transient phases e xisted in the above reaction, but the final phases of the reaction at 1350 degrees C were only TiB2 and beta-SiC. Futher, the TiB2-SiC compo site has been produced by reactive hot pressing at 2000 degrees C unde r 30 MPa for 60 min in an Ar atmosphere. The three-point bending stren gth and SENB fracture toughness of the composite were 332 MPa and 8.67 MPa m(1/2) respectively. According to the SEM analysis, it was sugges ted that the main toughening mechanism was stress induced microcrackin g.