LATERAL AND DEPTH PROFILES OF NITROGEN IN LASER-NITRIDED IRON

The effect of nitrogen take-up upon irradiation of iron or steel with excimer laser pulses in air or nitrogen atmosphere is well established . However, the influence of the laser parameters (energy density, time structure, wavelength, number of pulses) on the nitrogen profile is n ot yet understood. We used Resonant Nuclear Reaction Analysis to inves tigate the evolution of nitrogen profiles with the number of pulses, T o improve the accuracy of the nitrogen profiling, the laser irradiatio n was carried out in a N-15(2) enriched atmosphere. This allowed to de tect also very low nitrogen concentrations that made it possible to fo llow the development of the nitrogen depth profiles from 1 to 64 pulse s and to resolve the lateral nitrogen profiles across the laser spot. The laser induced surface morphology was observed with optical microsc opy and a surface profilometer.