Nanoindentation of boron-doped diamond on (001) crystal plane by molecular dynamics simulations

Boron-doped diamond is a crucial material for ultra-precision devices, with its mechanical properties and internal defect distribution being key factors that impact the efficiency and service life of such devices. This paper employs an innovative molecular dynamics method to analyze the nanoindentation process of boron-doped diamond with varying doping concentrations and crystal directions, offering valuable insights for the processing of boron-doped diamond. Firstly, a model of boron-doped diamond is built and nanoindentation simulations are conducted on the (001) crystal plane, with a comparative study for both 1 % boron-doped and pure diamond. Secondly, nanoindentation calculations and analyses are performed on the (001) crystal plane of diamonds doped with 0.1 %, 0.5 %, and 5 % boron to investigate the mechanical properties and dislocation evolution mechanisms across different boron-doping concentrations. Finally, the nanoindentation process of the (110) and (111) crystal planes of 1 % boron-doped diamond are calculated and analyzed to explore the crystal anisotropy in boron-doped diamond. The results show that boron-doped diamond exhibits higher Young's modulus, critical pressure, and stiffness compared to pure diamond. Furthermore, the equivalent von Mises stress on the stress concentration area and the quantity of dislocation during the nanoindentation loading process are reduced in boron-doped diamond compared to pure diamond. Meanwhile, the results demonstrate significant variations in the mechanical properties of diamond with different boron doping concentrations. The generation and diffusion mechanism of dislocations, as well as the type and quantity, do not exhibit consistency with increasing doping concentration. Moreover, our results suggest that (110) and (111) crystal surfaces have a lower critical pressure for inelastic deformation compared to (001) crystal surface, while their stiffness is higher. This study has the potential to advance the precision processing technology of boron-doped diamond.