Abstract :
This study focuses on the chemical, morphological and structural characterization of iron surfaces treated by laser in
ambient air. Incorporation of nitrogen over a 1–2 mm thickness (10–30 at.% at the profile maximum) and superficial
oxidation on 200–400 nm depth have been evidenced by nuclear reaction analyses. X-ray diffraction at grazing incidence
has shown the formation of FeO and Fe3O4 oxide phases as well as g-Fe(N), and E-FexN for a sufficiently high amount of
nitrogen incorporated. Treatments performed with different laser beams indicate that the parameter playing the major role in
surface modification processes is the wavelength. Nitrogen incorporation has been found to occur via the interaction of
reactive N, present in the laser-induced plasma, and the iron molten bath. The nitriding process is promoted in the IR
wavelength range. Oxidation takes place by chemical reaction during the cooling step, and is furthered in the case of UV
treatment.
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