Comparative research on atomic diffusion of diamond/Ni and MWCNTs/Ni interfaces with molecular dynamics and experimental methods

JB Dai and D Wei and ZB Wang and L Si and SY Cao and H Liu and ZJ Ye, CERAMICS INTERNATIONAL, 51, 5434-5450 (2025).

DOI: 10.1016/j.ceramint.2024.12.191

Diamond and multi-walled carbon nanotubes (MWCNTs) with excellent hardness and strength are the ideal reinforcement for tungsten carbide based ceramics due to the wear resistance and toughness enhancement effect. For the promising diamond-MWCNTs/WC-Ni composite, one of the major challenges is the intrinsic difference of interfacial bonding mechanism between diamond/Ni and MWCNTs/Ni interfaces that makes it difficult to obtain desired mechanical bonding properties simultaneously. To address this issue, the effects of holding time, holding temperature and doping elements on the atomic diffusion of diamond/Ni and MWCNTs/Ni interfaces were studied comparatively with molecular dynamics (MD) and experimental methods in this work. The results show that the diffusion process of diamond/Ni and MWCNTs/Ni system is asymmetric dominated by C atoms. The diffusion process of diamond/Ni system includes initial, rapid and stable diffusion stages, while MWCNTs/Ni interface only has rapid and stable diffusion stages. The interface width of diamond/Ni at 1423 K is 2.46 times that of 1223 K, and the interface width of MWCNTs/Ni at 1423 K is 1.55 times that of 1223 K. The addition of Cr increases the diamond/Ni interface width by 87.5 % and significantly decreases activation energy by 77.8 %. From the high-resolution transmission electron microscopy (HRTEM) images and the corresponding inverse Fourier transform images of the MWCNTs/Ni-Cr interface region, results reveal that the Cr doping atoms gradually diffuse to the defects of MWCNTs, prompting Cr7C3 to grow both horizontally and vertically through the chemical reactions between Cr and MWCNTs.

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