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

Mechanical properties of B4C–CrB2 binary eutectic composites prepared by arc‐melting

“…Figure 7 shows the effect of B 4 C content on the Vickers hardness ( H V ) and fracture toughness ( K IC ) on the cross section perpendicular to the growth direction of B 4 C–CrB 2 composites at a load of 9.8 N. The H V and K IC increased fast with increasing B 4 C content because B 4 C (31 GPa, 8 3.5 MPa m 1/2 7 ) has higher properties compared with CrB 2 (22.12 GPa, 11 3.44 MPa m 1/2 3 ). The H V and K IC at the eutectic composition showed the maximum value of 24.6 GPa and 4.3 MPa m 1/2 , which might have been attributed to the dense and uniform microstructure with submicron grain size.…”

“…Hence, the crack propagation is not easy at the eutectic interface. The propagation of the indentation crack at the eutectic composition was predominantly transgranular mode (Figure 8C 3,7,11,[35][36][37][38] extended in mixed transgranular and intergranular modes (Figure 8A,B). Branching and bridging, which consume energy of crack propagation, prevent the crack from expanding, as toughening mechanisms were also found in the microstructure.…”

“…Boron carbide (B 4 C) has also many excellent properties, for example, high hardness, good thermal stability, excellent wear resistance, and high-temperature oxidation resistance, as shown in Table 1. [6][7][8][9][10][11] In previous studies, B 4 C-CrB 2 dense composites have been prepared at higher than 2300 K for a soaking time more than 1 h by hot pressing (HP), 2,[12][13][14] pressureless sintering (PS), [15][16][17] and reactive PS 18 due to their strong covalent bonds and low diffusivity. However, high sintering temperatures can cause abnormal grain growth and microcracks, 19 reducing the mechanical properties of the composites.…”

“…As the brittleness, medium fracture toughness, and poor sintering property restrict the widespread use of monolithic CrB 2 in engineering applications, sintering additives are detrimental to overcome this problem. Boron carbide (B 4 C) has also many excellent properties, for example, high hardness, good thermal stability, excellent wear resistance, and high‐temperature oxidation resistance, as shown in Table 1 6–11 . In previous studies, B 4 C–CrB 2 dense composites have been prepared at higher than 2300 K for a soaking time more than 1 h by hot pressing (HP), 2,12–14 pressureless sintering (PS), 15–17 and reactive PS 18 due to their strong covalent bonds and low diffusivity.…”

Microstructure evolution and performance of B4C–NdB6 composites fabricated by in situ hot pressing

“…fabricated B 4 C–YB 4 composites with 3 wt% Y 2 O 3 addition, of which the relative density, hardness, flexural strength, and fracture toughness reached 97.00%, 34.84 GPa, 422.67 MPa, and 4.92 MPa m 1/2 , respectively. Besides, increasing the addition amounts of Y 2 O 3 (15 wt%) 21 can significantly promote the electrical conductivity of B 4 C ceramics from 570 Sm −1 (without Y 2 O 3 ) to 1400 Sm −1 , and increasing the addition amounts of Eu 2 O 3 (18 vol%) 22 can significantly improve the neutron‐absorption cross‐section of B 4 C ceramics from 614 barn (without Eu 2 O 3 ) to 819 barn, which promotes the capacity for neutron absorption.…”