High-speed plasma jet modification and doping of α-Fe

Abstract

Iron (α-Fe) samples were treated in a high-speed (up to 6 km/s) pulsed plasma jet using a plasmatron with a consumable (eroded) Mo electrode operated in specially selected regimes. As the number of jet pulses increases, the concentration of Mo within a 10-μm-thick surface layer of α-Fe varies in a nonmonotonic manner. In a 2-μm-thick layer, the oxygen content increases up to 50 at.%, while the concentrations of carbon and nitrogen do not exceed 10 at.%. The plasma jet treatment leads to the formation of a bcc Fe phase and the Fe7Mo6 and FeMo intermetallic phases in the surface layer. Doping the surface iron layer with molybdenum, as well as the formation of oxides and carbides, results in a 2.5-fold increase in the hardness of samples and in a decrease of wear under dry friction conditions.