The effects of Fe and $B_4C$ on the sintering behavior and mechanical properties of $TiB_2$ ceramics have been studied. The sintering was performed Ar atmosphere at 1900℃-2000℃ with attrition milled $TiB_2$ powder (mean particle size=1um ).
When small amount of Fe (0.5 wt.%) was added, abnormal grain growth of $TiB_2$ was occurred and the sintered density was low. It considered that grain growth rate was increased with the amount of Fe.
In case of $B_4C$ addition with 0.5 wt.% Fe, however, the abnormal grain growth was successfully suppressed, and it was considered that added $B_4C$ was acted as grain growth inhibitor. At this time, sintered density was increased up to 95% of theoretical density.
But with excess Fe addition ( 5 wt.%), $B_4C$ fails to serve as grain growth inhibitor and $B_4C$ grains were frequently observed to be trapped in abnormally grown $TiB_2$ grains.
The best mechanical properties were obtained for the $TiB_2$-10wt% $B_4C$-0.5wt% Fe ceramics, which showed 400 MPa of 3-point bending strength and 5.6 MPa $\sqrt{m}$ of fracture toughness.
