LIBS depth-profile analysis of W/Cu functionally graded material

Abstract

A feature of Laser-Induced Breakdown Spectroscopy (LIBS), the ability to perform depth profiling, has been exploited to analyze a tungsten‑copper functionally graded material (FGM), considered a relevant candidate for components in a nuclear fusion reactor. The proposed method relies on establishing correlations between the depth of ablation craters and the number of laser pulses, along with the accompanying LIBS spectra acquired by varying a number of laser pulses. LIBS measurements were performed using a Q-switched Nd:YAG laser at 532 nm with 100 mJ/pulse energy under reduced Ar pressure. The ablation craters were analyzed using optical profilometry. The copper concentration at each specific depth was assessed using a univariate calibration curve constructed with intensity ratios of Cu I 521.82 nm and W I 522.47 nm spectral lines. The calibration samples were pure W and homogenous W/Cu composite samples with different Cu content (10.9% - 35.3%) whose composition was determined by X-ray fluorescence. The proposed method exhibits potential applicability for quantitative analysis of multilayered materials.