Atomic-scale interfacial diffusion of diamond into titanium: Phase transition and layer dependence

Q Lin and SL Chen and Z Ji and ZW Huang and ZA Zhang and B Shen, SURFACES AND INTERFACES, 31, 101993 (2022).

DOI: 10.1016/j.surfin.2022.101993

The diffusion wear of diamond is a commonly recognized wear mode at high temperatures, while the atomicscale diffusion behavior and the initiation mechanism are scarcely reported. In this work, we conduct a reactive molecular dynamics study to unveil the diffusion mechanism of diamond into titanium from an atomistic perspective. It is found that substantial diffusion of carbon atoms into titanium at a nanoscale temperature occurs at the temperature over 3000 degrees C, and the diffusion intensifies rapidly with the further increase of temperature. By studying the evolution of the phase transition, we find that the dangling atoms with a coordination less than two play a critical role in initiating the diffusion of diamond, and subsequently more sp-bonded carbon phases are involved in promoting the diffusion process during the non-equilibrium period. Moreover, the diffusivity of carbon atoms in diamond is found to have a strong layer dependence, which can be attributed to the unique phase composition and activation energy for self-diffusion. Eventually, an effective activation energy for the interfacial diffusion from diamond to titanium of 543.9 kJ/mol is obtained. This study provides a new insight into the initiation mechanism of the interfacial diffusion of diamond materials.

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