Deconvolution of superimposing reaction signals from DSC curves in selected Al-Mg-Si-(Cu) alloys by mean-field modeling and HEXRD

• The late stages of the precipitation sequence in EN-AW 6061 and EN AW-6016 are thoroughly investigated, combining in-situ high-energy x-ray diffraction (HEXRD) and differential scanning calorimetry (DSC) data with mean field simulations. • The contributions of individual phases to the excess specific heat signal are modeled using mean field simulations of DSC cooling and heating experiments by considering a coarse and a fine population for each of the stable phases β-Mg2Si and Si, respectively. • The proposed combination of DSC, HEXRD, and mean-field simulations facilitates more sophisticated simulations in the future, for instance, by extracting the influence of certain microstructural features on individual phases and improving thermodynamic descriptions of metastable and stable precipitates. • The work further underlines the complexity of DSC measurements and their interpretation due to overlapping precipitation and dissolution reactions. The present work describes a systematic approach to improve mean-field simulations of dissolution and precipitation of precipitates from the late stages in the precipitation sequence in AlMgSiCu alloys for processing simulations. In addition to metastable precipitates, it considers the evolution of two populations (coarse and fine) of the thermodynamically stable phases in EN AW-6061 and EN AW-6016, β-Mg 2 Si and Si respectively. The setup is based on two previous publications on heterogeneous nucleation site energies and their distribution. The simulations are calibrated using data from continuous cooling and heating experiments obtained with differential scanning calorimetry (DSC) and high-energy X-ray diffraction (HEXRD). We show that mean-field simulations combined with DSC and HEXRD can provide valuable information to eliminate uncertainties related to, for instance, the thermodynamic description of metastable precipitates. The method described in this paper also delivers very reasonable results for the evolution of the individual phase fractions. It potentially facilitates the assessment of the influence of different types of nucleation sites and their densities.