Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1603392 | International Journal of Refractory Metals and Hard Materials | 2013 | 6 Pages |
Reaction process and phase formation mechanisms in reactive hot pressing (RHP) of titanium and boron nitride blend powders have been investigated in vacuum. In temperatures of up to 1300 °C, chemical reactions in the Ti–BN blend powder proceed via a solid-state diffusion process. Intermediate phases of hexagonal α-TiN0.3, tetragonal Ti2N, nonstoichiometric cubic TiN0.9 and orthorhombic TiB are found before they finally transform to the stoichiometric cubic TiN and hexagonal TiB2. Both the TiN–TiB2 ceramics reactive hot-pressed at 1600 and 1800 °C represent intragranular/intergranular distributions of TiB2 in TiN. In contrast with monolithic TiN and TiB2 ceramics, the reactive hot-pressed TiN–TiB2 exhibits a significant enhancement on flexural strength and fracture toughness. TiN–TiB2 ceramics reactive hot-pressed at 1800 °C have a Vickers hardness of 17.8 GPa, an elastic modulus of 475 GPa, a flexural strength of 732 MPa and a fracture toughness of 8.5 MPa·m1/2.
► Intermediate phases of α-TiN0.3, Ti2N, TiNx and TiB are found in TiN–TiB2 ceramics. ► TiN–TiB2 ceramics show intra-granular/inter-granular distributions of TiB2 in TiN. ► TiN–TiB2 ceramics reactive hot-pressed at 1800 °C have a high flexural strength of 732 MPa. ► TiN–TiB2 ceramics reactive hot-pressed at 1800 °C have a high fracture toughness of 8.5 MPa·m1/2.