Influence of starting temperature on differential scanning calorimetry measurements of an Al-Mg-Si alloy

This study investigates the effect of starting temperature on differential scanning calorimetry measurements of an Al-Mg-Si alloy. Linear heating experiments starting from 294 K to 423 K were performed at different heating rates directly after quenching. It is shown that the peak for the major strengthening phase beta '' is shifted to unexpected high values at low heating rates for a starting temperature of 294 K. The effect is supposed to be comparable to the well-known influence of room temperature storage after quenching on the precipitation of beta ''. As a consequence it is shown that methods to determine effective activation energies based on Kissinger-like analysis are restricted to measurement conditions where transformation mechanisms are not changed by the heating rate in Al-Mg-Si alloys. (C) 2013 Elsevier B.V. All rights reserved.