Densification kinetics, phase assemblage and hardness of spark plasma sintered Cu-10 wt% TiB2 and Cu-10 wt% TiB2-10 wt% Pb composites

The present work demonstrates the synthesis of Cu-10 wt% TiB2 composites with a theoretical density of more than 90% by tailoring the spark plasma sintering (SPS) conditions in the temperature range of 400-700 degrees C. Interestingly, 10 wt% Pb addition to Cu-10 wt% TiB2 lowers the sinter density and the difference in the densification behavior of the investigated compositions was discussed in reference to the current profile recorded during a SPS cycle. The sintering kinetics and phase assemblage were also discussed in reference to surface melting of the constituents prior to bulk melting temperature, temperature dependent wettability of Pb on Cu, diffusion kinetics of Cu as well as the formation of various oxides. An important result is that a high hardness of around 2 GPa and relative density close to 92% qtheoretical was achieved for the Cu-10 wt% TiB2-10 wt% Pb composite, and such a combination has never been achieved before using any conventional processing route.