Determination of surface hardness of ti-based alloys via laser induced breakdown spectroscopy (LIBS)‎

Abstract EN

Laser Induced Breakdown Spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique, which has been exploited to determine the surface hardness of a metallic alloy such as titanium-based alloy samples (Ti-6Al-4V).

It is 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 the Ti-based alloy samples.

In the present study, the proportionality relation has been demonstrated adopting different ionic and atomic spectral lines ratios from the corresponding LIBS spectra.

Additionally, the laser induced plasma parameters, namely the electron density and the plasma excitation temperature have been estimated as a function of the surface hardness of the adopted 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 adopted by conventional techniques.