Effect of Sn Addition on Microstructure and Electromagnetic Shielding Effectiveness of Mg-Gd-Y-Sn Alloys.

Microstructure, electromagnetic shielding effectiveness (SE), and mechanical properties of Mg-12Gd-3Y-xSn alloys were systematically studied to understand the effect of Sn addition on the structure and properties of the alloy. The experimental results show that the number of second phases increases after adding Sn, and Mg₂₄(Gd, Y)₅, Mg₅(Gd, Y), and Mg₂Sn phases are formed. The SE values of Mg-12Gd-3Y-xSn alloys increase gradually with the addition of Sn. Mg-12Gd-3Y-1.5Sn alloy subjected to artificial aging at 225°C for 36 h presents the SE value of 113-81 dB and a maximum increment in SE of 11 dB at 1500 MHz. The ultimate tensile strength of the aged Mg-12Gd-3Y-1.5Sn alloy at 250 °C can reach 345 MPa. When the incident direction of the electromagnetic wave is perpendicular to the basal plane, the Mg₂Sn phase precipitated parallel to the (0001)_α-Mg plane has more reflection area, which increases the SE value. The improved SE value is mainly due to the enhanced multiple reflection attenuations by the second phase. The precipitates β' and Mg₂Sn have high-temperature stability, making the alloy still exhibit good mechanical properties at 250 °C. [ABSTRACT FROM AUTHOR]