Revealing the underlying mechanism of abnormal grain growth in sub-rapid solidified Al-Mg-Si-Fe alloy

The dependence of abnormal grain growth (AGG) on initial solidification microstructure in the Al-Mg-Si-Fe alloy was investigated. The AGG was more prone to occur during annealing in the sample following the sub-rapid solidification (SRS, cooling rate ~ 200 K/s) route as compared to the counterpart undergoing conventional solidification (CS, ~18 K/s). It was verified to be closely related to the {100} 〈310〉 grain clusters containing high-mobility grain boundaries based on quasi in-situ microstructure analysis and the refined Mg2Si particles that can be easily dissolved in the SRS sample. This research provides insights for better understanding the close relationship between the AGG and SRS process.