Comparison between diffusion of 15N N and 14N in implanted iron

Abstract

It is well known that nitrogen implantations at doses greater than 10 17 ions cm −2 modify the tribological properties of metals. In particular the wear resistance for several types of steel is enhanced. Tribological tests and industrial applications are made with samples implanted with natural nitrogen which contains more than 99% of 14 N. On the other hand, physical properties, such as nitrogen diffusion in steels are measured using the 15 N(p, αγ) 12 C reaction at EP = 429 keV. However, it is also possible to measure depth profiling of 14 N with a narrow resonance at E α = 1531 keV in the 1 4N(α, γ)1 8 F reaction. Both reactions were used in the present work. Pure iron foils were implanted with enriched 15 N (70% 14 N–30% 15 N at different doses. Depth profiles of 14N and 15N were measured on the same sample before and after thermal annealing. The depth distribution was not affected by the isotopic composition of the implanted ions. There is no isotopic effect in the nitrogen diffusion during the implantation or after thermal annealing.