Shock compression behaviors of boron carbide (B[sub 4]C)

Hugoniot measurements on the highly dense, pure B(4)C polycrystal were performed by the inclined-mirror method to study the elastoplastic transition and to search phase transition. In inclined-mirror streak photographs, the smoothly jagged structure was observed at the free-surface shape in the plastic region. The Hugoniot-elastic limit (HEL) has been determined to be approximately 19.5 GPa. In the plastic region, a kink was observed at a particle velocity of around 1.26 km/s. The shock velocity (U(S))-particle velocity (U(P)) Hugoniot relations in the plastic region were given by U(S)=3.7+5.4U(P) km/s in the U(p) range of 0.54-1.26 km/s and U(S)=9.61+0.73U(P) km/s in the U(p) range of 1.26-4.3 km/s. The S value (0.73) in U(S)=C(0)+SU(P) above U(P)=1.26 km/s is significantly small compared with the result of Vogler [J. Appl. Phys. 95, 4173 (2004)], and was much smaller than those of many oxides and nitrides. This material behaved as an elastoisotropic solid above the HEL and showed a large and linear change in the pressure-density plot above 38 GPa (U(P)=1.26 km/s), which indicated the onset of a phase transition. (c) 2006 American Institute of Physics.