Establishment of Graded Hybrid Microstructure Through Centrifugal Casting of a Hypereutectic Al-Mg 2 Si Alloy

Content Provider	Semantic Scholar
Author	Aghazadeh, Ebrahim Samadi, Ahad Aghazadeh, Seifollah
Copyright Year	2018
Abstract	In this study, centrifugal casting method was used to produce a hyper-eutectic composite AlMg2Si with hybrid microstructure and graded hardness. For this purpose, two cylinders with a chemical composition of Al-20Si and Al-20Si-9Mg (weight percent) were cast using a vertical centrifugal casting machine. Then the microstructure and hardness of the cast cylinders were studied along the radial direction by optical and scanning electron microscopes and brinell method, respectively. The results show that in Al-20Si cast cylinder; in contrary to the outer layer which shows only a binary eutectic Al-Si microstructure, the inner layer contains a high volume fraction of in situ segregated primary silicon particles inside the eutectic matrix. By addition of 9% Mg to Al-20Si alloy, the inner layer of the cast cylinder form a hybrid microstructure containing of both Si and Mg2Si particles inside the eutectic matrix, while the outer layer shows only a ternary eutectic Al-Si-Mg2Si microstructure. As a result of these microstructure changes along the radial direction of the cylinders, not only the hardness of both cylinders are smoothly increased from the outer towards the inner layers, but also all radial sections of the Al-20Si-9Mg cylinder in compared with the other one, indicate higher hardness (about 18 brinell).
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Language	English
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Resource Type	Article