Morphology Development and Kinetics of Plate or Rod Shaped Precipitates in Aluminum Alloys

Microstructure quantitatively analysis is significant for building the relationship between microstructure and properties, especially the ageing precipitation kinetics in aluminum alloys. In the present paper, a core parameter (aspect ratio) was introduced to describe the morphology change of precipitation. Aspect ratios of T1-plate precipitates in Al-Cu-Li-Zr alloys, S-plate precipitates in Al-Cu-Mg alloys and β-rod precipitates in Al-Mg-Si alloys were quantitatively analyzed. Results indicate that aspect ratios of precipitates increase at the early stage of ageing, then reach the peak and finally decrease slowly. The soft-impingement theory and HHC theory were introduced to model the ageing kinetics. Thermodynamics and kinetics parameters of different precipitates were also calculated in the model. Simulated results of different precipitates agree well with the experimental results.