Effect of Friction Stir Processing on the Microstructure, Damping Capacity, and Mechanical Properties of Al-Si Alloy
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Friction stir processing (FSP) was conducted on an Al-Si casting alloy. The Si phase and Al grains of an Al-Si casting alloy were refined through FSP. Furthermore, FSP with high rotation rate led to the precipitation of Mg and Si atoms and the formation of Mg2Si phase in the Al-Si alloy. Precipitation improved the low-strain damping capacity but deteriorates high-strain damping capacity of the FSP sample at room temperature. At low rotation rate, the FSP sample exhibited excellent high-temperature damping capacity mainly because of its fine grain structure and the low density of its pinning points. The plastic instability of the Al-Si alloy was eliminated by FSP because of the refinement of the Si phase. The increase in the strength of each FSP sample was attributed to the increase in second-phase and boundary strengthening effects. Thus, the mechanical properties and damping capacity of Al-Si were enhanced after FSP.
KeywordsAl alloy capacity damping mechanical properties microstructure
This work was funded by the National Natural Science Foundation of China (No. 51601045), Guangxi “Bagui” Teams for Innovation and Research, the Guangxi Natural Science Foundation (No. 2016GXNSFDA380028), and the Guangxi Science and Technology Major Project (No. GKAA17202007).