Reaction synthesis and mechanical properties of TiB2-AlN-SiC composites

TiB2-AlN-SiC (TAS) ternary composites were prepared by reactive hot pressing at 2000 C for 60 min in an Ar atmosphere using TiH2, Si, Al, B4C, BN and C as raw powders. The distributions of Al and Si were not homogeneous, which shows that, to obtain a homogeneous solid solution of AlN and SiC in the composites, temperatures higher than 2000 C or time duration longer than 60 min are needed. Fracture toughnesses of about 6.35 MPa.m1/2 and 6.49 MPa.m1/2 were obtained in samples with equal molar contents of AlN and SiC. The highest fracture strength (470 MPa) was obtained in a sample, in which the volume ratio of TiB2/(AlN + SiC) was the nearest to 1 and there was finer co-continuous microstructure. 20 refs.