Phase transformation of cubic BN via spark plasma sintering

Abstract The phase stability of cubic boron nitride (cBN) at elevated temperatures is an important region for both pure BN and cBN‐based composite ceramics due to the significant property differences between distinct BN polymorphs. This study aims to explore the phase transformation behavior of cBN via the spark plasma sintering (SPS) process. It is revealed that the phase transformation from cBN to hBN favors an indirect phase transformation route with an intermediate phase of rBN. In addition, the phase transformed bulk BN through SPS exhibits high densification (∼96.7% of theoretical density), exceptional nanomechanical properties and good thermal conductivity. The fundamental study on the phase transformation of cBN, along with the excellent properties of dense BN bulks via the SPS process, provides a profound insight into BN‐related materials.