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

Abstract

In the field of specialty electronics and communications, there is a critical demand for magnesium (Mg) alloy sheets that possess exceptional mechanical properties and electromagnetic interference shielding effectiveness (EMI SE). This paper aims to develop a cost-effective and straightforward process for preparing a research proposal that combines excellent mechanical properties and EMI SE. After undergoing extrusion treatment, the Mg–6Zn–1La-0.5Zr alloy demonstrates an apparent bimodal microstructure, with an average grain size of approximately 2.55 μm. Subsequently, following a 37% rolling treatment, the grain size increases to about 5.29 μm. This increase in grain size is attributed to grain growth resulting from holding prior to the multi-pass rolling treatment. Notably, the Mg–6Zn–1La-0.5Zr alloy, subjected to extrusion and 75% rolling treatment, exhibits remarkable mechanical properties and EMI SE, with ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) values of 337.5 MPa, 227.3 MPa, and 12.5%, respectively. Furthermore, the EMI SE ranges from 79 dB to 110 dB within the frequency range of 30–1500 MHz. The exceptional mechanical properties are attributed to the synergistic effects of various strengthening mechanisms, including grain boundary strengthening, second phase strengthening, dislocation strengthening, heterogeneous deformation-induced strengthening, and texture. Similarly, the superior EMI SE is attributed to the alloy's higher electrical conductivity, strong basal texture, and uniformly diffused second phase.