Synthesis of nonstoichiometric high entropy Nb-added carbides

Fabrication and characterization of medium‐entropy carbide ceramics in low temperature sintering

“…In this study, the combination of multicomponent transition group metal carbides forms a single‐phase FCC solid solution, during which lattice distortion is caused by a mismatch between the atomic radius difference and the elastic modulus, and severe lattice distortion leads to the pinning of the dislocation, thus providing better strength 25 . Therefore, solid solution strengthening with a more stable interface structure has a positive effect on improving mechanical properties 24 . Csanãdi et al 26 .…”

“…In contrast to the medium-entropy (Ti,Zr,Ta)C ceramics with a relative density of 94.8% prepared by hot pressing at 2100 • C by Yang et al, 7 in this study, medium-entropy carbide ceramics with a relative density of 97% were obtained at a lower temperature. Generally speaking, the properties of ceramics are affected by the densities and grain sizes, 24 and (W,Ti,V)C 0.8 ceramics also have a good flexural strength at 1600 • C. The strength of interfacial bonding is a crucial factor in determining the flexural strength, and it was reinforced with the relative density increased. Moreover, the formation of FCC solid solution reduced the content of WC in sintering simples, which improved the plasticity of WC ceramics because the number of slip system in FCC phase is more than hexagonal close packed structure.…”

“…25 Therefore, solid solution strengthening with a more stable interface structure has a positive effect on improving mechanical properties. 24 Csanãdi et al 26 studied the strength and slip behavior of high-entropy carbide (Hf-Ta-Zr-Nb)C grains and found that this high-entropy (Hf-Ta-Zr-Nb)C has a hardness of 36 GPa, 27 which is much higher than its constituent components. Most importantly, the presence of carbon vacancies in TiC 0.4 increases the configurational entropy, which significantly decreases the mixing enthalpy of the solid phase, thus decreasing the Gibbs free energy, so that the sintering temperature is significantly reduced.…”

Effects of Nb/TiC/TaC/VC and Co addition on the microstructure and properties of WC‐based cemented carbides

“…As shown in Figure S1, the starting powder consists of Co (hexagonal closest packed [HCP] and FCC), Nb, WC, TiC, TaC, and VC. Nb dissolved into the metal lattice of carbides after sintering due to the similar lattice constant and entropy gain, and a multicomponent single‐phase solid solution (MS) Nb/TiC/TaC/VC was formed at higher temperatures ( G = H – TS ) 23 . There are two crystal structures for cobalt.…”

“…In the previous research, a series of nonstoichiometric high‐entropy carbides Nb/TiC/TaC, Nb/TiC/TaC/VC, and Nb/TiC/TaC/VC/WC with a high concentration of nonmetallic vacancies exhibited strong interfacial bonding between grains and dense microstructures at lower sintering temperatures of 1600°C−1700°C 23 . In this work, the nonstoichiometric multicomponent carbides Nb/TiC/TaC/VC and Co were added to WC to increase toughness while maintaining high hardness.…”