Mathematical Modeling of Mutually Influencing Elements by the Fundamental Parameter Method for X-Ray Fluorescence Analysis of High-Entropy AlCrFeCoNiCu Alloy

A mathematical model and a software program (FLUOR81) were developed to implement the fundamental parameter method for X-ray fluorescence analysis of new alloy types. The model takes into account the X-ray tube excitation by polychromatic radiation and the secondary excitation of some elements by others. The program was tested using state standard samples of steels and alloys with nickel and cobalt matrices to show that the intensity of characteristic lines could be calibrated using pure elements in the absence of standard samples. In this case, the relative measurement error was no more than 3-4%. This approach was employed for mathematical modeling of the mutual influence of elements in the AlCrFeCoNiCu high-entropy alloy (HEA). The stoichiometric coefficients in the AlCrxFeCoxNixCu alloy were varied (x = 0.5, 1, 2) to find that the relative deviations of initial concentrations of components (ignoring their mutual influence) from the stoichiometric values were within +/- 50% and slightly changed with concentration. These patterns can be used for semiquantitative estimates of the HEA compositions for which no standard samples are available. To obtain results with a relative error of 3-4%, calculations with the software developed are needed.