The Effect of Twins on the Mechanical Behavior of Boron Carbide

The microstructure and mechanical properties of boron carbide (B₄C) samples processed by slip casting were compared with those processed by the conventional hot-pressing technique. Although the quasi-static and dynamic mechanical experiments showed comparable results between the slip-cast and hot-pressed B₄C, scanning electron microscopy and electron backscattered diffraction of the B₄C samples revealed significant differences in the microstructure. A notable difference was the numerous growth twins in the slip-cast samples. The twin planes were determined to be { 10[`1] 1 } left{ { 10bar{1} 1} right} and consisted of 35 pct of the boundary population in the slip-cast B₄C but only 1 pct of the boundary population in the hot-pressed B₄C. It was hypothesized that the presence of twins will cause a different failure mechanism. The effect of the twins on the stress state was examined by finite-element simulations and will also be discussed.