High intensity, low ion energy implantation of nitrogen in AISI 5140 alloy steel

This paper presents the results of the formation of deep modified layers in AISI 5140 alloy steel using a high-intensity repetitively pulsed nitrogen ion beam. An arc generator with a hot cathode provided the DC nitrogen plasma flow. A plasma immersion approach was used for high-frequency, short-pulse very intense nitrogen ion beam formation. A grid hemisphere with radii of 7.5 cm was immersed in the plasma. Negative bias pulses with an amplitude of 1.2 kV, a pulse duration of 4 μs, and a pulse repetition rate of 10⁵ pulses per second were applied to the grid. The substrates were implanted at various temperatures ranging from 450 to 650 °C with 1.2 keV nitrogen ions using a very-high current density up to 0.5 A/cm² ion beams. The work explores the surface morphology, elemental composition, and mechanical properties of deep-layer modified AISI 5140 alloy steel after 60 min of low ion energy, very-high-intensity nitrogen ion beam implantation.