Influence of two-time hot pressing on microstructure and properties of TiB_2-Cu-Ni composite via combustion synthesis

TiB_2-40Cu-8Ni ceramic-metal composite with the relative density of about 90% was prepared by combustion synthesis. In order to improve the mechanical propertie,the two-time hot pressing sintering was conducted under at 1 200,1 250 ℃ and 1 300 ℃. The deformation behavior,microstructure and mechanical properties changes were investigated in detail. The results showed that the relative density and the flexural strength increased greatly after two-time hot pressing. The relative density reached 608 MPa and the flexural strength reached 96% at 1 300 ℃,and increased 12% and 5% respectively. The analysis of SEM indicated that the morphology of TiB_2 particle transformed from near equal axis-like shape to rod-like shape. The evolution of TiB_2morphology and growth mechanism was analyzed according to TiB_2 crystal structure characteristics.