Effect of Mechanical Stir on Microstructure and Electromagnetic Shielding Effectiveness of Mg-Al-Sn-Y Magnesium Alloy Cast Ingots
Mg-4Al-2Sn-0.1Y magnesium alloy cast ingots were prepared by mechanical stir-assisted pouring. And the microstructure, phase composition and electromagnetic shielding effectiveness were tested. The results show that compared with common casting, mechanical stir-assisted casting could make the microstructure smaller and compacter and improve the electromagnetic shielding effectiveness of the alloy. Moreover, the mechanical stir could make average grain size decrease by65.8%, and make electromagnetic shielding effectiveness at the efficiency of 300 MHz, 900 MHz, and 1500 MHz increase by15.8%, 26.5%, and 54.2%, respectively. But the phase composition is the same by the two methods and the alloy is both composed of α-Mg phase and a spot of Mg17Al12 phase and Mg2 Sn phase.