Preparation of Mg-6Zn-1Y-0.5Zr alloy sheet with excellent mechanical properties and electromagnetic interference shielding effectiveness by extrusion plus rolling

Magnesium (Mg) alloy sheets with excellent mechanical properties and electromagnetic interference shielding effectiveness (EMI SE) have great application prospects. This study investigates the microstructure, mechanical properties, and EMI SE of extruded and rolled Mg-6Zn-1Y-0.5Zr sheets. In the Mg-6Zn-1Y-0.5Zr alloy subjected to extrusion and rolling, the predominant internal second phases are Mg-Zn-Y and MgZn, with the volume fraction of the second phase increasing with cumulative strain. After the extrusion treatment, the average grain size of the Mg-6Zn-1Y-0.5Zr alloy was 2.7 μm. Increasing the rolling reduction to 37% resulted in an average grain size of 5.27 μm, while a rolling reduction to 75% decreased the grain size to 4.06 μm. The Mg-6Zn-1Y-0.5Zr alloys exhibited consistent trends in ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) under extrusion and various rolling strain treatments. These properties showed a relationship with cumulative strain, initially increasing and then decreasing. However, the EMI SE of the Mg-6Zn-1Y-0.5Zr alloy exhibited a positive correlation with cumulative strain. The sheets obtained through a combination of extrusion plus 37% rolling treatment exhibited excellent mechanical properties and EMI SE. The Mg-6Zn-1Y-0.5Zr alloy demonstrated UTS, YS, and EL values of 331.4 MPa, 251.3 MPa, and 18.7%, respectively. The EMI SE in the frequency range of 30–1500 MHz ranged from 79 dB to 113 dB, satisfying the requirements of the electronic information field regarding the mechanical properties and EMI SE of Mg alloy sheets.