Quantitative determination of solute concentrations in wrought aluminium alloys by combined electrical resistivity and multi-temperature thermoelectric power measurements
The concentration of alloying elements retained in solid solution is a key parameter controlling microstructure evolution and properties of wrought aluminium alloys. Quantitative determination of solute concentrations in multicomponent alloys remains challenging, however, because most available techniques either provide only local information or cannot separate the contributions of individual alloying elements. This paper presents a methodology combining low-temperature electrical resistivity and multi-temperature thermoelectric power (TEP) measurements for the quantitative determination of solute concentrations in wrought Al alloys. Element-specific temperature-dependent TEP coefficients were established using binary calibration alloys and incorporated into a numerical evaluation procedure based on the Nordheim–Gorter formalism. The resulting approach enables the simultaneous determination of multiple solute concentrations from a single set of resistivity and TEP measurements.Virtual validation experiments and sensitivity analyses confirm that the temperature dependence of the TEP response provides characteristic element-specific signatures that enable the separation of the contributions of individual alloying elements. Significant differences in sensitivity and information content were observed among the investigated elements, particularly for Si, and were found to govern the achievable accuracy and robustness of the calculated solute concentrations. Nevertheless, the principal alloying elements can generally be recovered with good accuracy. Application to experimental datasets confirms the robustness of the methodology and demonstrates its suitability for a wide range of non-heat-treatable Al alloys. The combined electrical-resistivity and multi-temperature TEP approach provides a rapid bulk-characterization technique for quantitative microchemistry analysis and a practical tool for alloy development, process optimization and microstructure modelling.