A good balance between mechanical properties and electromagnetic shielding effectiveness in Mg-9Li-3Al-1Zn alloy

It is still a challenge to develop MgLi alloy with a good balance of strength, plasticity and electromagnetic shielding effectiveness. Herein, a reasonable combination strategy for it was put forward through the processing steps: 1) dissolve the excess phase in the matrix by solid solution treatment, 2) promote the dynamic precipitation of the second phase and the formation of fine recrystallization by rolling, and 3) obtain the subgrain and more hard MgLi2Al and soft AlLi particles by subsequent aging treatment. Finally, the comprehensive improvement in strength, plasticity and electromagnetic shielding effectiveness of Mg-9Li-3Al-1Zn alloy was achieved. The ultimate tensile strength was increased by 34% compared to the as-cast alloy. The plasticity of the as-aged alloy was improved from 9.2% to 24.6% through the combination of the soft AlLi phase and subgrains, meanwhile, the electromagnetic shielding effectiveness at 1500 MHz was increased from 87 dB to 91 dB.