Quantitative analysis of elemental concentrations of aluminum alloys using calibration-free femtosecond laser-ablation spark-induced breakdown spectroscopy

Abstract

In this work, the calibration-free (CF) methodology combined with femtosecond laser-ablation spark-induced breakdown spectroscopy (fs LA-SIBS) was applied for the quantitative analysis of elements in aluminum alloy. A femtosecond laser (800 nm) operated at a repetition rate of 1 kHz with a pulse width of 35 fs was used as the laser-ablation source, and the plasma emission was enhanced by the spark discharge. Spectra were acquired using a compact fiber spectrometer coupled to a charge-coupled device and recorded at 200–500 nm. The aluminum alloy sample was mounted on a two-dimensional motion platform, and the effect of the sample moving speed on the spectral intensity was investigated. To evaluate the analysis performance of this technique, five standard aluminum alloy samples with certified elemental concentrations were tested. The average estimated electron density from these five transitions was (1.5 ± 0.3) × 1017 cm−3, which was determined by fitting the ion spectrum of Al II (281.62 nm) with Lorentz fitting. The plasma temperature was calculated to be 6300 ± 300 K using Saha–Boltzmann plots under the local thermodynamic equilibrium state. Trace elements with the content of <0.1% were detected by the proposed technique, and the analysis error of Al was <0.3%. This study shows that the CF fs LA-SIBS technique can be employed for quantitative analysis of major, minor, and trace elements in multi-composition alloys.