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Mechanical behavior of high entropy carbide ( HfTaZrTi )C and ( HfTaZrNb )C under high pressure: Ab initio study
Author(s) -
Jiang Shan,
Shao Lin,
Fan Touwen,
Duan JiaMing,
Chen XiaoTao,
Tang BiYu
Publication year - 2021
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.26509
Subject(s) - materials science , carbide , vickers hardness test , debye model , thermodynamics , bulk modulus , ductility (earth science) , density functional theory , shear modulus , elastic modulus , crystallography , composite material , computational chemistry , chemistry , physics , microstructure , creep
The evolution of structural, elastic, and electronic properties of high entropy carbide (HfTaZrTi)C and (HfTaZrNb)C under high pressure have been studied within the framework of density functional theory (DFT) in conjunction with special quasirandom structures. With increasing pressure, lattice constants of high entropy carbides (HfTaZrTi)C and (HfTaZrNb)C gradually decrease, so volumes shrink, and densities gradually increase. Under high pressure up to 200 GPa, elastic stiffness coefficients for both carbides are almost linearly hardened and meet the elastic stability criteria. With increasing pressure, elastic moduli and Debye temperature of both high entropy carbides (HfTaZrTi)C and (HfTaZrNb)C increase, while theoretical Vickers hardness decreases, although Vickers hardness of (HfTaZrNb)C is always higher than (HfTaZrTi)C in the whole pressure. The ductility of (HfTaZrTi)C and (HfTaZrNb)C is improved under pressure, and brittle‐ductile transition occurs at about 50 and 60 GPa, respectively. The electronic structure demonstrates that, with increasing pressure, covalent bonds between transition metal atoms and carbon atoms are strengthened, accompanying delocalization. This effect is responsible for high values of bulk modulus and shear modulus under pressure and enhanced ductility. The ionic bonds of both high entropy carbides weaken with increasing pressure, and (HfTaZrTi)C is affected more strongly by the pressure.