High-temperature toughening in ternary medium-entropy (Ta<sub>1/3</sub>Ti<sub>1/3</sub>Zr<sub>1/3</sub>)C carbide consolidated using spark-plasma sintering
Dmytro Demirskyi, Toshiyuki Nishimura, T. Suzuki, Yoshio Sakka, Oleg Vasylkiv, Kyosuke Yoshimi
Abstract
We report for the first time the effect of temperature on the mechanical properties of (Ta1/3Ti1/3Zr1/3)C carbide. Flexural strength and fracture toughness were investigated using the three-point bending technique in argon. Using commercially available carbide powders with an equimolar ratio and performing spark plasma consolidation at 1973°C, we obtained a bulk single-phase medium-entropy carbide ceramic with the lattice parameter a= 4.458 Å. The flexural strength and fracture toughness at room temperature reached on average 700 MPa and 3.2 MPa m1/2, respectively. At 1800°C, local decomposition of the medium-entropy carbide took place as a structure with a local chemical gradient was observed after high-temperature tests, which increased fracture toughness by 30% (to 4.4 MPa m1/2).