Preparation of B4C‐Based Multiphase Composites with Binary Y2O3 and Nd2O3 Sintering Aids by Spark Plasma Sintering

Abstract

The densification behavior and mechanical properties of B4C‐based composite ceramics were tailored by introducing Y2O3–Nd2O3 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 B4C and the oxides produced secondary phases including (YNd)B6, (YNd)B4, (YNd)3C4, (YNd)BO3, and B2O3, with (YNd)B6 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•m1/2. These results demonstrate an effective approach for controlling phase formation and improving the mechanical performance of B4C‐based composite ceramics.