Atom probe tomography of early natural aging and pre-aging of AA 6016Wednesday (08.11.2017) 15:20 - 15:40 Part of:
Early stages of low temperature aging in Al-Mg-Si alloys are experimentally difficult to observe. In this study a new strategy for the measurement of the as-quenched condition and various initial stages of aging via atom probe tomography (APT) was applied to the alloy AA6016. To hinder uncontrolled aging at room temperature after quenching, sample preparation and sample transfer into the atom probe analysis chamber was performed under cryogenic conditions. However, the quantification of early stage clusters is still challenging due to the spatial noise of the APT data, the low detector efficiency, and the artifact of surface migration of Si in the vicinity of low-index crystallographic poles during the APT experiments. The analyzed data were corrected for artifacts and customized APT data analysis was applied to maximize the value of the description of solute clustering. Cumulative relative radial distribution function analysis and the core linkage algorithm were applied. The resulting distribution of solutes after very early stages of natural aging is compared quantitatively to the solute distributions for pre-aged and long term natural aged states. It was found that the Mg – Mg aggregation increases the most for the pre-aged material, but also Si – Mg and Si – Si aggregation was detected.