Sintering behaviour of ultra-fine titanium diboride powder prepared by self-propagating high-temperature synthesis (SHS) technique

A systematic study on the sintering behaviour of titanium diboride (TiB2) powder of different particle sizes prepared by a SHS route is carried out in the temperature range of 1973-2173 K. The decrease of particle size increases the densification of the TiB2 powder compacts and a maximum densification of 93% of the theoretical density is achieved after sintering at 2173 K. The activation energies for sintering are observed to vary within ∼76 to 85 kJ/mol for the different particle sizes that indicate the boron diffusion in Ti as the possible rate-controlling process for sintering. The time dependent variation of densification under isothermal condition indicates the surface diffusion or vapour phase condensation mechanisms operative in the system. The microstructure and microhardness of different sintered samples reflect the densification behaviour of sintered pellets.