Clustering and precipitation in Al-Mg-Si alloys during linear heating

•Custom-made heating device ensures reproducible linear heating to samples with various geometries, thus enabling characterisations of the clustering and precipitation processes during linear heating using in situ electrical resistivity measurement, ex situ positron annihilation lifetime measurements, DSC, hardness, HAADF-STEM.•Quenched-in excess vacancies play an important role in cluster formation during linear heating.•Linear heating at lower temperatures can harden the alloy more than isothermal ageing at a higher temperature for the same time.•Cluster hardening is linearly related with DSC heat release.•A new explanation for the often observed double-β″-peak in DSC traces is proposed.