The developments of high-performance alloys ask for a strict control on the contents of trace elements. However, the measurement of trace elements in high-performance alloys is still a challenge due to their complex constituent and interference. Nowadays, the trace elements such as boron (B) and phosphorus (P) in iron-based and nickel-based high-performance alloys can be determined only by chemical method which has the disadvantages of complex, time consuming and asking for specially trained operators.

Aimed to address the challenges in developing high-performance alloys, the group for Advanced Laser Manufacturing Technology which belongs to Wuhan National Laboratory for Optoelectronics has studied in resonantly-excited laser-induced breakdown spectroscopy (LIBS) based on a wavelength-tunable laser. They found that B I 208.96 nm could be selectively enhanced by reheating the laser-induced plasma using 249.77 nm excitation from a wavelength-tunable laser. In this way, the boron line of B I 208.96 nm can be enhanced for 5.8 times and the intensities of background spectra were not changed. Using this resonant-exciting method, the group resolved the problem of determining trace boron in nickel-based superalloys and steels by LIBS for the first time, with limit-of-detections (LoDs) of boron were 0.9 and 0.5 ppm, respectively. The results showed that resonantly-excited LIBS has not only satisfied national standards for determining boron in high-performance alloys, but also has the advantages of simple, fast, capabilities of micro-analysis and online analysis, and it would hopefully be applied in practice.

This study was financially supported by the National Special Fund for the Development of Major Research Equipment and Instruments (No. 2011YQ160017) of China, and the National Natural Science Foundation of China (No. 61575073, 51429501 & 61378031). The results have been published in Optics Express (Vol.24, Issue. 8, pp.7850-7857, 2016).