Microanalysis of a ductile iron by microchip laser-induced breakdown spectroscopy

Laser beams with ns pulse width are generally employed as an excitation source in the process of detecting inclusions and elemental segregation on a workpiece surface by microanalysis of the laser-induced breakdown spectroscopy. In addition, the ablation crater interval of laser sampling on the sample surface is generally 20 μm or more. It is difficult to detect the morphology of inclusions smaller than 50 μm in diameter and the micro-segregation of elements. However, in this work, when the laser ablation crater is 10 μm and the sampling resolution of the laser on the sample surface is 5 μm, the morphology and distribution of spherical inclusions (20–60 μm) in ductile iron can be detected according to the difference of the Fe spectrum on the Fe matrix and the spheroidal inclusions. Moreover, the distribution of micro-segregation of Mg and Ti elements in ductile iron was also studied.