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The unique mechanical properties and local lattice distortion (LLD) for hexagonal close‐packed (HCP) multiple principal element alloys (MPEAs) are very rarely studied so far. Employing density functional theory calculation based on special quasirandom structure, this work studies the influences of LLD on elastic properties for both novel hexagonal TiZrHf(Sc) MPEAs. Compared to the pristine structures, the lattice stability of distorted random structures is improved evidently. Moreover, LLD obviously lessens the shear elastic properties, which may be an ubiquitous phenomenon irrespective of the lattice types of MPEAs. These results also uncover the apparent improvement in malleable behavior and shear anisotropy for HCP MPEAs. So, the influence of LLD on elastic properties for HCP MPEAs is profound. The degree of LLD is further studied via the standard deviation of near‐neighbor (NN) and next NN bond length distributions as an effective indicator of LLD. More significant distortion uncovered in TiZrHf alloy corresponds consistently to the stronger effects of LLD in TiZrHf alloy. Bader's charge and charge density distribution also demonstrate the underlying impact on LLD for both HCP MPEAs, so electronic nature is a significant factor for LLD. The present study provides guideline for designing mechanical properties of TiZrHf‐based HCP MPEAs engineering materials.

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.