Effect of Sn on as-cast ageing behavior
of Al-Si-Mg alloy
of Al-Si-Mg alloy
(1. The Key Laboratory of Liquid Structure and Heredity of Materials,
Ministry of Education, Shandong University, Ji＇nan 250061, China;
2. Department of Materials Science and Technology,
Shandong Architectural Engineering Institute, Ji＇nan 250014, China)
Ministry of Education, Shandong University, Ji＇nan 250061, China;
2. Department of Materials Science and Technology,
Shandong Architectural Engineering Institute, Ji＇nan 250014, China)
Abstract: The effect of minor additions of Sn on the as-cast ageing behavior of Al-11Si-0.35Mg alloy was investigated. It is shown that precipitation has been retarded in Sn containing alloy and more time is needed to reach its peak hardness，which is bigger than that of the base alloy. Analysis of the kinetic data shows that Sn addition does not change the growth dependent parameter n, but increases the nucleation density dependent parameter k. TEM results show that there are little precipitates in Sn containing alloy at the initial stage of as-cast ageing. However, the Sn addition increases the net density of precipitates during as-cast ageing, because there are many dislocation loops formed as ageing progresses and Sn segregated at the edges of dislocation loops, which acts as the nuclei of precipitates.
Key words: aluminum alloy; as-cast ageing; precipitates; nucleation density