Phase transformation of high speed steel after sequential nitrogen and boron high current density ions implantation

The present work continues the study of double high current ion implantation (HCII) of nitrogen and boron into AISI M2 high speed steel. The additional investigations of phase-structure state by conversion electron Mössbauer spectroscopy, glancing X-ray diffraction, Auger electron spectroscopy and tribological properties of steel were carried out. HCII of nitrogen is found to form precipitates of ε-Fe2+x(N,C) (x=0.67, 1) and α″-Fe16(N,C)2 carbonitrides and causes strong sputtering of surface. Boron HCII forms boron film (20 nm in thickness) on the surface of steel. The best tribological properties were revealed for the N+B variant of HCII. The 2.2 times improvement of wear-resistance was reached because of surface boron films and carbonitrides enriched sublayer influence.