Effect of strontium on crystallization
of Mg2Si phase in Al-Si-Mg casting alloys
of Mg2Si phase in Al-Si-Mg casting alloys
(1. Department of Mechanical Engineering, Southeast University,
Nanjing 210018, China;
2. College of Materials, Nanjing University of Technology,
Nanjing 210009，China)
Nanjing 210018, China;
2. College of Materials, Nanjing University of Technology,
Nanjing 210009，China)
Abstract: Optical microscope and SEM were used to observe the changes of the microstructure of Al-11.6%Si-0.4%Mg alloys with varying strontium additions and the effect of strontium on the crystallization of Mg2Si phase was discussed. It is found that Mg2Si phase nucleates on the surfaces of the eutectic silicon flakes in the unfully modified alloys, growing as meshwork or bamboo-shoot shape, however, very few and fine Mg2Si particles phase are isolated at the boundaries of the eutectic cells in the fully modified alloys. Strontium has an important influence on the crystallization of Mg2Si phase in Al-Si-Mg casting alloys and it is thought to be related to the increase of the amount of dendritic α phase and the modifying degree of eutectic silicon phase.
Key words: Al-Si-Mg alloy; strontium modification; Mg2Si; crystallization