Preparation of high-entropy nitride composites with fine grain size and high relative density

Abstract

High-entropy ceramics have great potential for different applications due to their unique properties. However, the optimization of grain size and densification on high-entropy ceramics has still not been investigated. This study utilized raw material design and high-energy ball milling technology to create a kind of (Ti19.28V17.77Cr17.11Zr6.29N39.56)92.32(ZrO2)7.68 high-entropy nitride composites with fine grain size and high densification. It displayed that CrNx could be prepared from raw material Cr2N by high-energy ball milling technology, which could decompose at lower temperatures, thus promoting the formation of high-entropy ceramic solid solutions. The study demonstrated the importance of CrNx via the comparation of CrNx in high-entropy systems (Ti19.28V17.77Cr17.11Zr6.29N39.56)92.32(ZrO2)7.68 with CrN in high-entropy systems (Ti18.6V17.82Cr12.12Zr7.08N44.36)93.93(ZrO2)6.07. Using XRD, SEM, EDS, displacement monitoring, and the phase diagram calculated by Thermo-Calc, the differences between the two systems were explored, particularly in terms of mechanical properties and grain size. The study showed that the grain size of (Ti19.28V17.77Cr17.11Zr6.29N39.56)92.32(ZrO2)7.68 was controlled within 3 μm, with densification of 98.78 %. The Vickers hardness, bending strength, and fracture toughness at room temperature reached an average of 2248HV0.5, 200 MPa, and 9.428 MPa m1/2, respectively. The study highlighted the importance of selecting specific materials and combining them with corresponding preparation processes to achieve joint optimization of densification and grain size.