Correlation between the microstructural evolution of a 6061 aluminium alloy and the evolution of its thermoelectric power

Abstract The thermoelectric power (TEP) of a 6061 Al alloy was measured during isothermal ageing performed between 200 and 500°C. A correlation between the change in TEP and the precipitation kinetics of various metastable phases was established using TEM and HRTEM observations and resistivity measurements. It was demonstrated that the TEP kinetics allow an assessment of the residual concentration of solute in the final equilibrium state. Furthermore, it was shown that the non-monotonous TEP changes reflect the microstructural transformations occurring in the alloy. In particular, the transition between two phases can be detected, owing to the change of the intrinsic effect or of the chemical composition of the precipitates.