Reaction Synthesis and Mechanical Properties of TiB 2–AlN–SiC Composites

Abstract

TiB 2–AlN–SiC (TAS) ternary composites were prepared by reactive hot pressing at 2000°C for 60 min in an Ar atmosphere using TiH 2, Si, Al, B 4C, BN and C as raw powders. The phase composition was determined to be TiB 2, AlN and β-SiC by XRD. The distribution of elements Al and Si were not homogeneous, which shows that to obtain a homogeneous solid solution of AlN and SiC in the composites by the proposed reaction temperatures higher than 2000°C or time duration longer than 60 min are needed. The higher fracture toughness (6·35±0·74 MPa·m 1/2 and 6·49±0·73 MPa·m 1/2) was obtained in samples with equal molar contents of AlN and SiC (TAS-2 and TAS-5) in the TAS composites. The highest fracture strength (470±16 MPa) was obtained in TAS-3 sample, in which the volume ratio of TiB 2/(AlN+SiC) was the nearest to 1 and there was finer co-continuous microstructure. ©