AES INVESTIGATIONS OF THE IRON SURFACE-COMPOSITION AFTER LASER IRRADIATION UNDER ATMOSPHERIC CONDITIONS

The laser induced modification of iron surfaces with atmospheric speci es was investigated by means of Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). Different laser systems were used for irradiating iron samples in a wide range of the laser processing p arameters up to small foci and ultra shea pulses. A nitriding of iron connected with an oxidation of the near surface region was observed in the wavelength range between 193 nm and 10.6 mu m using large foci (s imilar to 0.1 cm(2)) and short pulses (10...1400 ns). In case of small foci (similar to 7.10(-6) cm(2)) with ns-pulses (50 ns) an enrichment of the iron melt with nitrogen and an advanced oxidation of the surro unding area of the laser spot were detected. When using shorter pulses (200 fs, 40 ps) no indications for a nitriding were found.