Molecular dynamics simulations on crack propagation in TiZrHfTa and TiZrHfNb alloys

ZM Li and CL Xu and PD Li and XB Tian and WT Jiang and QY Wang and HD Fan, ENGINEERING FRACTURE MECHANICS, 327, 111443 (2025).

DOI: 10.1016/j.engfracmech.2025.111443

Refractory high-entropy alloys (RHEAs) have exceptional mechanical performances at high temperatures, which are considered as a potential candidate for high-temperature structural materials. In this work, molecular dynamics simulations were employed to study the Mode-I crack behaviors in pure Ta, pure Nb, TiZrHfTa alloy and TiZrHfNb alloy. Four cracks with different orientations were considered. The crack behaviors and plastic deformation modes at the crack tip were investigated as well as their temperature effects. Simulation results show that most of the cracks in pure metals propagate in a brittle cleavage manner, while the cracks in HEAs propagate difficultly due to the plastic deformation, such as dislocations, recrystallization and slip bands. Although the critical stress intensity factors of HEAs are lower than those of pure metals, the increase rates of stress intensity factors are higher, suggesting that the HEAs are more ductile. As the temperature increases, the critical stress intensity factors of pure metals mostly decrease while those of HEAs mostly change weakly. The brittle-to-ductile transition temperature of HEAs is lower than that of pure metals.

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