Morphology and thermal stability of metastable precipitates formed in an Al-Mg-Si ternary alloy aged at 403 K to 483 K

Morphology and thermal stability of metastable phase precipitates formed in a balanced (Mg/Si=2) Al-Mg-Si alloy were studied by means of high-resolution electron microscopy (HRTEM) observations and differential scanning calorimetry (DSC) measurements. The present study revealed that the four types of precipitate morphology were found in the HRTEM images, that the heat change of the exothermic peak P in DSC measurements was mainly caused by the formation of type-2 and 3 precipitates in morphlogy and that the heat change of the exothermic peak Q which was yielded after the peak P probably corresponded to the formation of type-4 precipitates.