Enhanced Electromagnetic Interference Shielding in a Duplex-Phase Mg–9Li–3Al–1Zn Alloy Processed by Accumulative Roll Bonding

High electromagnetic shielding performance was achieved in the Mg–9Li–3Al–1Zn alloy processed by accumulative roll bonding (ARB). The microstructure, electromagnetic interference shielding effectiveness (SE) in the frequency of 30–1500 MHz and mechanical properties of the alloy were investigated. A model based on the shielding of the electromagnetic plane wave was used to theoretically discuss the EMI shielding mechanisms of ARB-processed alloy. Results indicate that the SE of the material increases gradually with the increase in the ARB pass. The enhanced SE can be attributed to the obvious microstructure orientation caused by ARB, and the alternative arrangement of alpha(Mg) phase and beta(Li) phase. In addition, with the increase in ARB pass, the number of interfaces between layers increases and the grain orientation of each layer tends to alignment along c-axis, which is beneficial to the reflection loss and multiple reflection loss of the incident electromagnetic wave.