Influence of vanadium content on the microstructural evolution and mechanical properties of (TiZrHfVNbTa)C high-entropy carbides processed by pressureless sintering

A series of (TiZrHfVNbTa)C high-entropy ceramics with different vanadium contents have been fabricated by pressureless sintering at 2300 degrees C-2500 degrees C for 1 h, utilizing self-synthesized carbide powders obtained by carbothermal reduction. The addition of vanadium is beneficial to promote densification process and refine grain, as well as facilitate the homogeneous distribution of metal elements. The distribution of pores is also modified, almost entirely existing at grain boundary, and the integral mechanical properties achieve optimization. However, excess adding vanadium does not favor forming a single-phase (TiZrHfVNbTa)C high-entropy ceramic. The optimal (TiZrHfVNbTa)C high-entropy ceramic sintered at 2300 degrees C possesses a high relative density of 97.5 % and homogeneous microstructure with small grain size of 1.2 mu m. The flexural strength and Vickers hardness reach 473 MPa and 24.9 GPa, respectively. This work has established a cost-effective and convenient preparation of novel (TiZrHfVNbTa)C high-entropy carbide ceramics.

Automated summary

A series of (TiZrHfVNbTa)C high-entropy ceramics with varying vanadium contents were fabricated using carbothermal reduction, with the addition of vanadium enhancing densification, refining grain size, and improving mechanical properties. Excessive vanadium, however, prevented the formation of a single-phase structure. The optimal ceramic exhibited high relative density, uniform microstructure, small grain size, and impressive mechanical properties.