Effect Of Secondary Phases On The Electromagnetic Shielding Effectiveness And Mechanical Properties Of Mg-Zn Magnesium Alloy

In recent years,with the rapid development of electronic science and technology,electronic products have been updated more rapidly,digital systems have been used more frequently,and electromagnetic radiation pollution has become a very serious problem worldwide.Magnesium alloy is the lightest engineering structural material today,and its good electromagnetic shielding performance is its merit that deserves attention.However,the mechanical properties of magnesium alloys are generally lower than that of aluminum alloys,and the lower mechanical properties hinder the future development of magnesium alloys.The second phase strengthening is one of the main strengthening methods to improve the properties of the alloy,and the second phase in the magnesium alloy will also affect its electromagnetic shielding performance.Therefore,this paper will explore the second relative law of the electromagnetic shielding performance and mechanical properties of magnesium alloys to provide a basis for the development of magnesium alloys with both high electromagnetic shielding and good mechanical properties.In this paper,Mg-Zn-Y sheets with LPSO phase and Mg-Sn-Zn-Ca-Ce sheets with different contents of Zn and Sn were prepared to study the structure,electromagnetic shielding and mechanical properties of LPSO phase,Mg Zn₂ phase and Mg₂Sn relative to magnesium alloy Law of influence.The main experimental results are as follows:(1)With a fixed Y/Zn atomic ratio of 1.34,a magnesium alloy containing LPSO phase was obtained in the Mg-Zn-Y alloy system.As the content of the 18R-LPSO phase rises,the strength of the as-cast Mg-Zn-Y alloy was improved,the plasticity droped sharply,the electromagnetic shielding performance in the low-frequency band decreased,and the electromagnetic shielding performance in the high-frequency band increased.(2)After annealing at 530?,Mg-Zn-Y alloy precipitates lamellar 14H-LPSO phase.Compared with the bulk 18R-LPSO phase distributed near the grain boundary,the orientation of the lamellar 14H-LPSO phase tended to be consistent.Improve the electromagnetic shielding performance of the alloy.The main reason is the orderly arrangement of lamellar 14H-LPSO phases,which increases the internal interface,hinders the propagation of electromagnetic waves in the magnesium matrix,enhances the reflection loss and multiple reflection loss,and thus improves the electromagnetic shielding performance.(3)In the Mg-Sn-Zn-Ca-Ce alloy,when the incident wave is perpendicular to the base surface,the electromagnetic shielding performance gradually increased with increasing Sn content,and gradually decreased with increasing Zn content.The reason was that when the incident wave was perpendicular to the base surface,the Mg Zn₂phase precipitated along the cylindrical surface during the aging process could not increase the reflection loss,and the disc-shaped Mg₂Sn phase precipitated along the base surface could increase the reflection loss.The second phase precipitated on the flat surface had better electromagnetic shielding effect than the second phase precipitated on the other surface,so that the electromagnetic shielding performance of the alloy could be improved.The peak aging state Mg-3Sn-2Zn-0.2Ca-0.3Ce alloy had the best comprehensive performance:electromagnetic shielding efficiency up to 92d B(frequency 1200MHz),tensile strength 352MPa,elongation 8.1%.Mg-Sn-Zn-Ca-Ce alloy sheet had better mechanical properties,electromagnetic shielding performance was higher than the requirements of commercial standards and had excellent industrial application prospects.