Proceeding from the results of the previous subsection, let us restrict our attention to specimens with a density of (4.50±0.05) g/cm3 and consider the flexural strength σf of the material. A significant dependence on the grain size is readily seen in the results at room temperature. While this figure contains a mixture of data from three-point and four-point test methods using differing specimen sizes and crosshead speeds, the comparison suggests that the strength σf decreases as the grain size increases. This result is at least consistent with reports that specimens prepared with grain size g > 15 µm exhibit spontaneous microcracking in the microstructure, which would tend to reduce the strength of the material. At elevated temperatures, the slope of σf concerning T appears to be nearly constant for temperatures less than 1500 °C and does not depend significantly on density, grain size, or test method. The average value of the slope is (∂σf/∂T) = (0.06±0.02) MPa/K. Two effects have been suggested for the increase of strength with temperature. Strength may increase due to the relaxation of residual internal stresses produced in the specimens by the anisotropic thermal expansion of the microcrystalline constituent particles. Crack healing due to oxidation and the formation of B2O3 may also contribute to this behavior for temperatures up to about 1000 °C; room temperature strengths of specimens oxidized at higher temperatures appear to be diminished by oxidation. In general, the fracture strength of a brittle material is limited by microstructural inhomogeneities, commonly called flaws. If you are looking for high quality, high purity, and cost-effective Titanium diboride, or if you require the latest price of Titanium diboride, please feel free to email contact mis-asia.