Preparation of B 4 C‐Based Multiphase Composites with Binary Y 2 O 3 and Nd 2 O 3 Sintering Aids by Spark Plasma Sintering

ABSTRACT The densification behavior and mechanical properties of B 4 C‐based composite ceramics were tailored by introducing Y 2 O 3 –Nd 2 O 3 rare earth oxide additives during spark plasma sintering. The effects of additive content and sintering temperature on phase evolution, microstructure, and mechanical performance were systematically investigated. The additives promoted liquid phase formation and significantly enhanced densification. High temperature reactions between B 4 C and the oxides produced secondary phases including (YNd)B 6 , (YNd)B 4 , (YNd) 3 C 4 , (YNd)BO 3 , and B 2 O 3 , with (YNd)B 6 forming preferentially. Increasing the additive content and sintering temperature led to a rise, followed by a decline, in relative density, hardness, flexural strength, and fracture toughness. At 1800°C, the composites achieved a flexural strength of 337 MPa and a fracture toughness of 2.73 MPa•m 1/2 . These results demonstrate an effective approach for controlling phase formation and improving the mechanical performance of B 4 C‐based composite ceramics.