Toughening in low-dimensional nanomaterials high-entropy ceramic nanocomposite

Very recently, high entropy concept has evolved from metal to the ceramic community, named as high entropy ceramics (HEC). The configurational entropy endowed the system with unique structure, performances as well as application potentials such as aerospace, high-speed machining tools, and nuclear reactors. However, the poor densification together with low fracture toughness of HEC significantly limited the practical applications of HEC. Herein, we report for the first time the employment of low-dimensional nanomaterials including multilayer graphene (MLG), carbon nanotube (CNT) and SiC nanowire (SiC_nw) to improve the densification coupled with fracture toughness of HEC through two-step spark plasms sintering. HEC-MLG and HEC-SiC_nw exhibited flexural strength of 671.3 MPa and 626.5 MPa, with fracture toughness of 7.1 MPa m^1/2 and 6.2 MPa m^1/2, respectively. The strength and toughness of HEC nanocomposites were both greater than those of the reported values for high entropy ceramics. The reinforcing mechanisms were discussed in detail for all the three HEC nanocomposites. Overall, this paper demonstrated that the toughening methods for normal ceramics were also feasible for HEC matrix, significantly increasing the freedom to tailor the properties and applications of HEC.