Molecular dynamics simulation of the tensile response and deformation mechanism of diamond/TiC combinations

Abstract

The diamond materials combine several prominent intrinsic performances, such as high transmittance, low microwave dielectric loss, and so on. A nanoscale carbide layer will be indispensably produced on their surface to guarantee the diamond can be wetted by metallic parts, for example the diamond microwave window for use in thermonuclear fusion reactor. The mechanical performance of the diamond/carbide layer interfacial bonding, which remains unknown because of dimensional limitation, will be critically vital. In this work, molecular dynamics (MD) simulation was conducted to explore the fracture mechanism of diamond/TiC combinations under uniaxial tension. The deformation behavior of (001), (110), and (111) single-crystalline (SC) TiC on diamond was investigated based on the stress–strain curve, fracture process, and dislocation evolution. The crystallographic orientation-dependent fracture modes were revealed. For the case of TiC(001) and TiC(110), the plastic fracture happened. The TiC{111} dislocations would be first emitted from the interface. Different dislocation morphologies were presented, such as stair-rod dislocations and dislocation tangles for TiC(001), as well as geometrically necessary dislocations for TiC(110). For the TiC(111), the brittle fracture took place because most easily activated slip planes were perpendicular to the force direction. Our findings revealed the nanomechanical behaviors and corresponding deformation mechanisms of the diamond/TiC combinations, facilitating the design and development of nanostructured combinations with superior mechanical performance.