Strain-induced strengthening in superconducting β-Mo2C through high pressure and high temperature

High-strain-induced microstructural refinement and dislocations are critical for the strengthening of metallic materials; however, this is difficult to achieve in ceramic materials due to their unique bonding characteristics and electronic structure. Here, a series of beta-Mo2C bulk ceramics are consolidated by the high pressure and high temperature (HPHT) strategy. Our results demonstrate that high strain-induced grain plastic deformation at high pressure produces a lamellar sub-grain structure with high-density dislocations, and that the dislocations at the lath-like grain boundaries eventually evolve into low-angle grain boundaries. The mechanical properties, superconducting behavior, and onset of oxidation of the specimens are investigated. It is found that supercon-ductivity and hardness arise from the high density of states at the Fermi level, while the high intrinsic hardness is attributed to the strong hybridization between Mo-4d orbitals and C-2p orbitals. Furthermore, strain-induced defect structure (dislocations and low-angle grain boundaries) mainly mainly enhances the intrinsic structure of beta-Mo2C.

Automated summary

The study demonstrates that high-strain-induced plastic deformation in ceramic materials leads to the formation of a lamellar sub-grain structure with high-density dislocations and the evolution of dislocations into low-angle grain boundaries. The high density of states at the Fermi level and the strong hybridization between Mo-4d and C-2p orbitals contribute to the superconductivity and hardness of the material. The strain-induced defect structure (dislocations and low-angle grain boundaries) enhances the intrinsic structure of the material.