Effect of Pulse Magnetic Field on Primary Silicon in Al-20Si Alloy

Due to its good wear resistance, Al-20Si is widely used as piston. But coarse primary silicon greatly undermines the mechanical properties of Al-Si alloy. The primary silicon could be refined in pulse magnetic field with suitable magnetic flux density and magnetic field frequency. In this work, the microstructure of Al-20Si alloy with and without pulse magnetic field treatments was observed, and the influence mechanism of weak pulse magnetic on the microstructure of the alloy was investigated. The results showed that the grain size of primary silicon fluctuated with increasing magnetic flux density at 1Hz. The smallest grain size of primary silicon is obtained at 94mT. The grain size of the primary silicon decreased with increasing magnetic field frequency under the magnetic flux density of 94mT.