Effects of Multilayer Electromagnetic Stirring on the Microstructure and Properties of a Hypereutectic Al-Si Alloy

A hypereutectic Al-Si alloy was prepared by a custom-made multilayer electromagnetic stirring process. The effects of different process parameters on the microstructures and properties of wear-resistant aluminum-based materials were studied through optical microscopy, scanning electron microscopy and X-ray diffraction mechanical tests. The results showed that the optimum composition of the alloy is Al17Si4Cu1.5Mg1.5Ni according to JMatPro calculations. For primary Si, its average particle size (28 μm) was the smallest, its shape factor (0.64) was the largest, and its roundness was the highest when using multilayer reverse stirring. The tensile strength, elongation and microhardness values reached 308 MPa, 1.93% and 152 HV, respectively, under the optimal process. Multilayer electromagnetic stirring strengthened the relative melt motion between different layers, caused melt turbulence and particle collision, promoted uniform solute and temperature distributions, strengthened heat transfer, improved the nucleation rate and refined primary Si.