الفهرس 
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Abstract
Laser induced breakdown spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique. However, it has been shown recently that it is possible to use LIBS for the surface hardness determination of solid targets. In the present work LIBS is exploited to determine the surface hardness of two different types of metallic alloys, a titanium based alloy (Ti-6Al-4V) and an iron based alloy (Fe93Ni4Ti3). It has been shown that there is a direct proportionality relation between the ionic to atomic spectral lines intensity ratios and the surface hardness values measured mechanically via Vickers hardness test for different samples of both alloys. Such proportionality has been demonstrated adopting different ionic and atomic spectral lines ratios from the LIBS spectra of the samples of both alloys. However, it has been proven that the intensity ratio of the ionic to atomic lines Ti II 444.38 nm / Ti I 398.97 nm can be used to determine the surface hardness for both Ti-6Al-4V and Fe93Ni4Ti3 alloys. The laser induced plasma parameters, namely the electron density and the plasma temperature have been also estimated as a function of the surface hardness of the different alloy samples. The obtained direct proportionality between the plasma temperature and the samples surface hardness has been interpreted in view of the increased collisions in the plasma plume due to the strong repulsive forces for harder targets. On the other hand, such high repulsive force leads to fast expansion of the laser induced plasma plume and consequently to a decrease in the electron number density in agreement with the inverse proportionality obtained between the surface hardness and the electron density. The results obtained in the present work demonstrate the potential of using LIBS in metallurgical and industrial applications for the direct determination of different alloys surface hardness, saving time and cost of conventional techniques.