Understanding the intrinsic properties of metal borides is an attractive research topic in materials science. Here, we perform a computational study on the indentation shear strengths and the atomic-scale structural changes of TaB2 under indentation shear deformations based on the CALYPSO method and first-principles calculations. Abnormal strain-stiffening behaviors are found in both hexagonal P6/mmm and orthorhombic Cmmm phases of TaB2 due to the TaB12 hexagonal prisms combined with the adjacent Ta–Ta metallic bonds along the [110] direction that form a robust three-dimensional configuration, which resists the large shear deformations under Vickers indentation loading conditions. Our calculations show that the indentation shear strengths of both P6/mmm and Cmmm phases of TaB2 credibly exceed the 40 GPa threshold for superhard materials. These findings provide powerful guidelines for future experiments to synthesize and design the ideally orientated TaB2 samples and other new kinds of superhard materials.
Zirconium and hafnium nitrides are charmingly hard superconductors [X. J. Chen et al. Proc. Natl. Acad. Sci. U.S.A., 2005, 102, 3198] with specific application under extreme conditions. Understanding the intrinsic hardness, especially under Vickers indentation deformation, in these superconductors is very important. Here, we perform first-principles studies of the stress–strain relations and deformation mechanisms of ZrN and HfN under compressive, tensile, pure shear, and indentation strains. The results offer a comprehensive description of their versatile stress responses, and the calculated indentation shear strengths for ZrN and HfN agree well with experimental results. The superior performance characteristics of HfN, compared to the isostructural ZrN, is attributed to the higher valence electron concentration that strengthens the Hf–N bonds. These results reveal the atomistic mechanisms for the mechanical properties of ZrN and HfN, providing insights for further exploration of hard and ultrahard transition-metal compounds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.