Microstructure of ultrahigh dose nitrogen-implanted iron and stainless steel

Nitrogen ion implantation of pure Fe and AISI 304 stainless steel to doses as high as 1x1019 N2+/cm2 while the target is held at elevated temperatures between 100 and 600degC leads to layers of various N-containing phases as identified by conversion electron Moessbauer spectroscopy and X-ray diffraction. Very thick layers, compared to the ballistic implantation depth, containing γ'-Fe4N can be produced by holding the Fe targets near 400degC while even thicker layers containing either ε-(Fe, Cr, Ni)2+xN, γ-phase high N solid solution, or mixed α-phase/γ-CrN can be produced in 304 stainless steel depending on the dose and provided the average temperature during implantation is near or above 400degC. Nearly complete retention of the implanted dose is observed in 304 SS. (orig.)