Nuclear microprobe analysis of wear tracks on 14N-implanted steels

Two nuclear microbeam analysis techniques [3,7 MeV (α, p) and 6 MeV (α, α)] have been used to determine the local areal density of 14N which remains in wear tracks resulting from pin-on-disc testing of nitrogen implanted 15-5 PH and 304 stainless steels. The microbeam analysis shows that the extent of N migration into the 15-5 substrate was to depths < or approx. 0.5 μm, but perhaps to < or approx. 1.0 μm in 304. The as-implanted layer in 15-5 PH contains up to 40-45 at.% N and consists principally of proportional 2 μm particles of (Fe, Cr)2Nsub(1-x). When sufficient wear has occurred in 304 to lower the N content below 1017 N/cm2, an O buildup to 2 x 1017 O/cm2 is observed; however the presence of N does not correlate with low O levels in the wear tracks of 15-5 PH. (orig.)