Determinations of trace boron in superalloys and steels using laser-induced breakdown spectroscopy assisted with laser-induced fluorescence.

Boron (B) is widely applied in microalloying of metals. As a typical light element, however, determination of boron in alloys with complex matrix spectra is still a challenge for laser-induced breakdown spectroscopy (LIBS) due to its weak line intensities in the UV-visible-NIR range and strong spectral interference from the matrix spectra. In this study, a wavelength-tunable laser was used to enhance the intensities of boron lines selectively. The intensities of B I 208.96 nm from boron plasmas were enhanced approximately 3 and 5.8 times while the wavelength-tunable laser was tuned to 249.68 and 249.77 nm, respectively. Utilizing the selective enhancement effect, accurate determinations of trace boron in nickel-based superalloys and steels were achieved by laser-induced breakdown spectroscopy assisted by laser-induced fluorescence (LIBS-LIF), with limits of detection (LoDs) of 0.9 and 0.5 ppm, respectively. The results demonstrated that LIBS-LIF can hopefully be used in boron determinations and has great potential for improving the ability of LIBS to determine light elements in alloys with a complex matrix.