Laser nitriding of iron and aluminum

Samples of pure iron and pure aluminum have been irradiated in nitrogen atmosphere with a pulsed nanosecond excimer laser in the UV wavelength range. For iron, almost all the phases predicted by the Fe–N equilibrium phase diagram are observed, while in aluminum the wurtzite AlN phase is formed. The dimension of the laser spot (typically 5×5 mm2), the number of laser pulses (1–512), the laser beam fluence (1–8 J/cm2) and the pressure of the reactive atmosphere (0.01–10 bar) strongly affect the nitrogen depth profiles and the characteristics of the resulting compounds. Therefore, the influence of these experimental parameters has been systematically investigated. A detailed study of the nitrogen incorporation as a function of the number of pulses and the beam fluence allowed us to model the experimental results giving some important hints on the nitriding process.