Heat treatment for precipitation hardening is known to have a large effect on the nano/micro-structure of cast aluminum alloys, and hence its properties. In the present work, precipitation kinetics after solutionizing and water quenching has been characterized by differential scanning calorimetry, transmission electron microscopy observations (TEM) and microhardness evaluations at different aging conditions. The Kissinger methodology was applied with the Lee-Kim-Starink-Zahra (LKSZ) kinetic equation in order to extract the kinetic parameters from DSC runs at constant heating rates, assuming that the precipitates have an ellipsoidal shape. TEM results showed evidence of semi-coherent θ' precipitation in accordance with the microhardness evolution during isothermal aging at 190°C and kinetic analysis from DSC data. The size and number density of precipitates were measured and counted on bright field TEM images taken on specimens aged at two different times. Activation energies for the precipitation kinetics of θ and θ' were found to be equal to 330 kJ/mol and 114 kJ/mol respectively. Finally, values for the interfacial mobility have been determined from the kinetic parameters derived from the DSC results and the TEM observations.

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