Thermal stability and precipitate microstructures of Al−Si−Mg−Er alloy
Yi He, Hai-hui XI, W.Q. Ming, Qinqin Shao, Ruohan Shen, Yuxiang Lai, Cuilan Wu, Jianghua Chen
Abstract
The effect of Er on the microhardness and precipitation behavior of the heat-treated Al−Si−Mg alloy was investigated by microhardness tester and TEM. As a comparison, the influence of natural aging was also studied. It is shown that the thermal stability of the over-aged Al−Si−Mg−Er alloy is highly related to the average size of the precipitates. The average size of β’’ precipitates in Al−Si−Mg−Er alloy is smaller than that in Al−Si−Mg alloy, and the distribution is more localized under condition of without introducing natural aging. However, when natural aging is introduced before artificial aging, the Al−Si−Mg−Er alloy has similar average size and distribution of precipitates with the Al−Si−Mg alloy, resulting in similar mechanical properties. The effect of Er on the precipitation kinetics in the alloy was also discussed in detail to explain these phenomena.