Exploring the Mechanical Anisotropy and Ideal Strengths of Tetragonal B?CO?.

ABSTRACT: First-principles calculations were employed to study the mechanical properties for the recently proposed tetragonal B?CO? (t-B?CO?). The calculated structural parameters and elastic constants of t-B?CO? are in excellent agreement with the previous results, indicating the reliability of the present calculations. The directional dependences of the Young's modulus and shear modulus for t-B?CO? are deduced in detail, and the corresponding results suggest that the t-B?CO? possesses a high degree of anisotropy. Based on the strain-stress method, the ideal tensile and shear strengths along the principal crystal directions are calculated, and the obtained results indicate that the shear mode along (001)[100] slip system dominates the plastic deformation of t-B?CO?, which can be ascribed to the breaking of the ionic B-O bonds. The weakest ideal shear strength of 27.5 GPa demonstrates that the t-B?CO? compound is not a superhard material, but is indeed a hard material. Based on the atomic explanation that the ternary B-C-O compounds cannot acquire high ideal strength, we propose two possible routes to design superhard B-C-O compounds.

SUBMITTER: Zheng B 

PROVIDER: S-EPMC5459106 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature