Microstructure and Electromagnetic Shielding Properties of Mg-Zn-Ce-Y-Zr Alloys

摘要

Microstructure and electromagnetic interference shielding properties of extruded Mg - Zn - Ce - Y - Zr alloys were systematically investigated. A bimodal grain structure of fine recrystallized grains and deformed grains was observed in the alloys. Yttrium (Y) and cerium (Ce) refined the recrystallized grains. Mg - Zn - Ce phase, Mg~(3)Zn~(3)Y~(2)phase and a few precipitates containing Zn and Zr were observed. Y and Ce additions changed the texture of the alloys. When the total rare earth content reached 4 wt.%, the texture was remarkably weaker than other studied alloys. The shielding capacity increased first and then decreased with Y contents. The value of shielding effectiveness for the extruded Mg - 5Zn - 1Ce - 2Y - 0.6Zr alloys reached 79-118?dB in the frequency range of 30?MHz-1.5?GHz, which was significantly higher than that of some aluminum alloys. The addition of Y and Ce is effective in improving the shielding capacity in Mg alloys. The electrical conductivity and second phases in the alloys were important in enhancing shielding effectiveness. The texture and precipitation exerted significant effect on electrical conductivity. In addition, subsequently aging treatment evidently improved shielding effectiveness.