Competition between densification and microstructure development during spark plasma sintering of B 4 C–Eu 2 O 3

The densification of nonoxide ceramics has been a known challenge in the field of engineering ceramics. The amount and type of sinter‐aid together with sintering conditions significantly influence the densification behavior and microstructure in nonoxide ceramics. In this perspective, the present work reports the use of Eu 2 O 3 sinter‐aid and spark plasma sintering towards the densification of B 4 C. The densification is largely influenced by the solid‐state sintering reactions during heating to 1900°C. Based on the careful analysis of the heat‐treated powder mixture (B 4 C–Eu 2 O 3 ) and sintered compacts, the competitive reaction pathways are proposed to rationalize the formation of EuB 6 as dominant microstructural phase. An array of distinctive morphological features, including intragranular and intergranular EuB 6 phase as well as characteristic defect structures (asymmetric twins, stacking faults and threaded dislocations) are observed within dense B 4 C matrix. An attempt has been made to explain the competition between microstructure development and densification.