Influence of two-time hot pressing on microstructure and properties of TiB₂-Cu-Ni composite via combustion synthesis

TiB₂-40Cu-8Ni ceramic-metal composite with the relative density of about 90% was prepared by combustion synthesis. In order to improve the mechanical properties, the two-time hot pressing sintering was conducted under at 1200°C, 1250°C and 1300°C. The deformation behavior, microstructure and mechanical properties changes were investigated. The results showed that the relative density and the flexural strength increased after two-time hot pressing. The relative density reached 608 MPa and the flexural strength reached 96% at 1300°C, and increased by 12% and 5% respectively. The analysis of scanning electron microscopy (SEM) indicated that the morphology of TiB₂ particle transformed from near equal axis-like shape to rod-like shape. The evolution of TiB₂ morphology and growth mechanism were analyzed according to TiB₂ crystal structure characteristics.