Dependence of Nb doping on microstructure and mechanical properties of Al2O3/Ti3SiC2 composites

In this work, the Al 2 O 3 /Ti 3 SiC 2 composites with different Nb doping amounts (0–5 vol%) were prepared by vacuum hot pressing sintering (30 MPa, 1450 for 1 h). Various tests and characterization had been performed on samples to investigate the dependence of Nb doping on the mechanical properties and microstructure of Al 2 O 3 /Ti 3 SiC 2 composites. Nb doping can optimize the microstructure of Al 2 O 3 /Ti 3 SiC 2 composites. Scanning electron microscopy (SEM) images showed that with the increase in Nb doping, the pores of the composites gradually decreased and the microstructure became denser. Based on X-ray diffraction (XRD) pattern analysis, it was found that Ti 3 SiC 2 may react with Nb to form the enhanced phases Ti 5 Si 3 , TiC and Nb 3 Si. Therefore, with the continuous doping of Nb, more toughening phase Ti 3 SiC 2 will be converted to the strengthening phases, leading to the sacrifice of partial fracture toughness to improve the bending strength and hardness of Al 2 O 3 /Ti 3 SiC 2 composites.