Deformation behavior of BN diamond-like phases

Boron nitride (BN) diamond-like phases represent the recently proposed family of three-dimensional fully sp3‑hybridizedmech materials, similar to diamond and cubic boron nitride. Such structures are very promising for protective coatings; thus, the understanding of their mechanical behavior requires more attention. In this work, molecular dynamics is used to investigate the deformation behavior of BN diamond-like phases under hydrostatic tension. Two classes of BN diamond-like phases based on hexagonal BN layers (LA) and BN nanotubes (tubulanes, TA) are considered. Detailed analysis of the deformation behavior reveals four distinct deformation stages: elastic, two inelastic regimes with different mechanisms, and pre-critical regime. Deformation is governed by the cooperative mechanisms of interatomic bond elongation and valence angle rotation, with fracture initiated by the rapid elongation of one of the bonds in the pre-critical regime. All studied phases exhibit high mechanical strength, with fracture pressures ranging from 106 to 193 GPa. The LA4 phase demonstrates the highest strength of 193 GPa and slightly different deformation behavior. For LA phases, a clear correlation is found between the density and strength. The obtained results provide an atomic-level insight into the mechanical behavior of novel BN diamond-like phases and suggest their promising potential for the use in high-strength applications, particularly as advanced protective coatings.

1. Work is supported by the Ministry of Science and Higher Education of the Russian Federation (State Assignment of IMSP RAS) -