EFFECT OF SINTERING TEPMERATURE ON MICROSTRUCTURE OF Ti6Al4V MATRIX COMPOSITES

(TiBw+TiCp)/Ti6Al4V composites were fabricated by reactive hot-pressing at the temperature range of 800~1200°C using the starting materials of TiB2, C and Ti6Al4V powders. The XRD results suggested that the reaction between C and Ti happened 900°C and above, while the reaction between TiB2 and Ti happen at 1100°C and above. SEM results also suggested that the reaction between C and Ti was prior to that between TiB2 and Ti. With the increase of the sintering temperature, the size of TiC particle and TiB whisker reinforcements increased gradually. The TiC particle was formed at the boundaries of original Ti6Al4V particles, while the TiB whiskers grew toward the inside of Ti6Al4V particles, which resulted in a strong bonding between neighboring Ti6Al4V particles. The results of hardness and relative density tests showed that the (TiBw+TiCp)/Ti6Al4V composites sintered at 1100°C had the highest hardness and relative density compared with that sintered at other temperatures.