The effect of efficient high-dose-rate plasma immersion ion implantation on microstructure and properties of 8Cr4Mo4V steel

8Cr4Mo4V steel was implanted with 20 keV nitrogen ions dose rates with fluences between 2.60 x 10(17) ions/cm(2)center dot h and 1.04 x 10(18) ions/cm(2)center dot h. The samples were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), elemental dispersive spectroscopy (EDS), secondary ion mass spectroscopy (SIMS), auger electron spectroscopy (AES) and nanoindentation test. The stopping and range of ions in matter (SRIM) code was used to calculate vacancies and displacements distributions. The results reveal that the implanted surface layer contains the phase composition of Fe(M) and Fe2-3N. The peaks of the samples with a dose rate from 2.60 x 10(17) to 7.85 x 10(17) ions/cm(2)center dot h are broadened and slightly shift to left by 0.777 degrees towards comparing to the dose rate of 1.04 x 10(18) ions/cm(2)center dot h. A significant improvement in roughness of Ra (similar to 10.4 nm) is attained for the dose rate of 7.85 x 10(17) ions/cm(2)center dot h. The lattice parameters of the smallest grain size, the highest micro-strain and dislocation density of 11.78 nm, 7.716 x 10(-3) and 1.559 x 10(16) /m(2) respectively were obtained for the dose rate of 5.18 x 10(17) ions/cm(2)center dot h. There exists a deep diffusion zone of about 400 nm for the dose rate of 7.85 x 10(17) ions/cm(2)center dot h and 1.04 x 10(18) ions/cm(2)center dot h, which is 4 times deeper than other implanted samples. Furthermore, the nanohardness of implanted samples improved notably as well, especially at the dose rate of 8.64 x 10(17) ions/cm(2)center dot h, reaches to a higher value of 16.3 GPa, which is 46.8 % higher than that of non-implanted sample of 11.1 GPa, implies that the properties of samples strongly affected by the implantation dose rate.