Simultaneous achievement of high electromagnetic shielding effectiveness (X-band) and strength in Mg-Li-Zn-Gd/MWCNTs composite

Abstract

In this study, the Mg-9Li-3Zn-0.5Gd/MWCNTs composite was prepared by the method of heat treatment+electrophoretic deposition (EPD)+accumulative roll bonding (ARB), and the microstructure, electrical conductivity, electromagnetic (EM) shielding properties in the X-band (8.2–12.4 GHz) and strength were evaluated. The microstructure characterization shows that, after five ARB cycles, MWCNTs are uniformly distributed in the Mg-Li matrix, and severe plastic deformation promotes the dynamic precipitation of the nano-scale secondary phase particles, which greatly weakens the lattice distortion of the Mg-Li matrix. Besides, MWCNTs induces a large amount of ultrafine nano-scale W-phase precipitation. The property evaluation indicates that the electrical conductivity, ultimate tensile strength and yield strength of C-ARB5 sheet are 7.60 MS/m, 280 MPa and 264 MPa, respectively, which are increased by 1.9%, 4.2% and 4.9% compared with ARB5 sheet. In the X-band frequency range, the electromagnetic interference (EMI) shielding effectiveness (SE) of ARB5 sheet is 77–96 dB, and that of C-ARB5 sheet is increased to 89–100 dB. The improvement of C-ARB sheets property is mainly attributed to the uniformly distributed MWCNTs inducing precipitation of ultrafine nano-scale W-phase.