The effects of in-situ formed phases on the microstructure, mechanical properties and electrical conductivity of spark plasma sintered B4C containing Y2O3

B4Cs without additive and 5, 10 and 15 wt % Y2O3 containing B4Cs were produced by using spark plasma sintering (SPS) technique at different temperatures such as 1820, 1930 and 2030 °C and the effects of in-situ formed phases on the mechanical properties and electrical conductivity of B4C were investigated. Microstructural investigations showed that the YB4 phase was formed at 1820 °C and the YB6 phase at 1930 °C. The hardness values of B4C-YB4 composites were higher than the value of B4C sintered at 1820 °C while lower than that of sintered at 2030 °C. The fracture toughness steadily increased with increasing Y2O3 content. The electrical conductivity of B4C sintered at 2030 °C increased by ∼ 40 % with the contribution of in-situ formed YB4 phase. Compared to B4C-YB4, B4C-YB6's hardness was higher, while its fracture toughness and electrical conductivity were lower.