Determination of the various phases of aluminium in steel by x‐ray fluorescence spectrometry

The total content of aluminium in steel can be determined from the Kα line in the x-ray spectrum with a detection limit of 0.001%. However, aluminium is generally present in three phases, as metal, as nitride and as oxide; these different phases are of metallurgical significance and have to be distinguished. This is possible from their different kβ bands in the x-ray spectrum, which were found at 1555.3 1553.9 and 1552.5 eV, respectively. The physical bandwidth of about x-ray 7 eV, however, causes overlapping of the peaks, so that an unfolding procedure is needed. The defection limit of the different phases was determined to be 0.06% which, unfortunately, is above the region of interest for modern steel analysis. In addition, the analysis time of about 3 min is too long for use in process control, so that the classical methods for pahse determination cannot be replaced by x-ray fluorescence analysis.