In situ observation of the dynamic precipitation of Mg2Sn in Mg-Sn binary alloy processed by controlled aging treatment

Abstract

The dynamic precipitation and growth of Mg₂Sn in a binary Mg-9.76wt.%Sn alloy aged in the temperature range of 180 °C-330 °C were observed in real time by applying in situ transmission electron microscopy techniques, showing the details where and how precipitates nucleate, grow, or dissolve. The dispersive nanoparticles were observed in the Mg matrix at 180 °C, then gradually grew to a lath-like shape on the basal plane at 240 °C-250 °C. The dynamic re-dissolution process of precipitates at the appropriate temperature of 300 °C-330 °C was observed, which was also found to mainly be related to temperature, aging time, surface tension, and vacancies. Meanwhile, a new orientation relationship between the stable precipitates and the Mg matrix was revealed. The results will give a significant insight into the microstructural factors regarding the formation of the orientation relationships, and provide a theoretical guidance for the optimization of alloy performance.