Phase, microstructure and related mechanical properties of a series of (NbTaZr)C-Based high entropy ceramics

Toughening (NbTaZrW)C high‐entropy carbide ceramic through Mo doping

“…Lattice parameters (Table 1) of this series of HECCs, (NbTaZrWMo x )C ( x = 0, 5, 10, 15, and 20), were determined to 4.4836, 4.4714, 4.4654, 4.4554, and 4.4503 Å, respectively, according to XRD pattern. The value of (NbTaZrW)C is consistent with our previous report 35 . The lattice constants obtained from DFT calculations agreed well with the experimental values.…”

“…The Hume‐Rothery‐based size misfit parameter ( δ ) 16 is well‐known empirical criteria for describing the comprehensive effect of the atomic size difference in the multicomponent materials, including HECs and alloys. It has been successfully applied to evaluate the formation possibility of numerous other multi‐cation carbides 17,35,49 . We, thus, followed the typical expression (Equation ) to calculate the values of $$\delta $$(Table 1) for each of the studied HECCs: $$\begin{equation}\delta {\rm{\ }} = \sqrt {\mathop \sum \limits_{i = 1}^n {c_i}{{\left( {1 - \frac{{{r_i}}}{{\bar{r}}}} \right)}^2}} \ \end{equation}$$where $$n$$is the metal carbide component species in the metal carbide solid solutions, $${c_i}$$is the atomic percentage of the $$i$$component in the metal carbide, $${r_i}$$is the lattice constants of the metal carbides, and $$\bar{r} = \mathop \sum _{i = 1}^n {c_i}{r_i}\ $$.…”

“…Recently, we 35 successfully synthesized single‐phase ternary‐cation (NbTaZr)C, quaternary‐cation (NbTaZrW)C and (NbTaZrHf)C, and quinary‐cation (HfNbTaWZr)C carbides using spark plasma–sintering technique and investigated their mechanical properties. The hardness and fracture toughness of this series of HECCs also exhibited superiority compared to conventional binary carbides and other reported HECCs.…”

Local Lattice Distortion in High-Entropy Carbide Ceramics

“…Different from single phase equimolar quinary HEAs with S config ~1.61 R, the salt-rock HEC structure has two sublattices, and the configuration entropy on the sublattice model is ~0.8 R. While in order to show the high configuration entropy of HECs, the quinary HECs have S config ~1.61 R, according to the new configuration metric [18]. To study the effect of alloying elements on the properties of HECs, the (Ti 0.33 Zr 0.33 Nb 0.33 )C ternary carbide [19], (NbTaZr)C-based HECs [20] and (Hf 0.25 Ta 0.25 Zr 0.25 Ti 0.25 )C, (Hf 0.25 Ta 0.25 Zr 0.25 Nb 0.25 )C, (Zr 0.25 Ta 0.25 Nb 0.25 Ti 0.25 )C quaternary HECs were reported [21]. Li et al found that in the quinary HECs, the W and/or Hf addition produces a large effect on the hardness and fracture toughness of (NbTaZr)C-based HECs [20].…”

“…To study the effect of alloying elements on the properties of HECs, the (Ti 0.33 Zr 0.33 Nb 0.33 )C ternary carbide [19], (NbTaZr)C-based HECs [20] and (Hf 0.25 Ta 0.25 Zr 0.25 Ti 0.25 )C, (Hf 0.25 Ta 0.25 Zr 0.25 Nb 0.25 )C, (Zr 0.25 Ta 0.25 Nb 0.25 Ti 0.25 )C quaternary HECs were reported [21]. Li et al found that in the quinary HECs, the W and/or Hf addition produces a large effect on the hardness and fracture toughness of (NbTaZr)C-based HECs [20].…”