Plasma immersion ion implantation for improvement of mechanical properties of AISI M2 steel

Plasma immersion (PI3) ion implantation of AISI M2 steel by nitrogen was carried out. The implantation voltage was 40 kV and the doses varied in the range of 2–8×1018 ions/cm2. It is established that the hardness of steel increases up to 25 GPa, the friction coefficient decreases by the factor of 2 and wear resistance is enhanced by a factor of 10 after PI3. It is explained by the formation of a highly doped face-centered-cubic γ-Fe(N,C) phase that is due to local tempering of the steel surface. The total concentration of nitrogen and carbon in this phase is about 40 at. %.