Study On Electromagnetic Shielding Effectiveness And Mechanical Properties Of Mg-Zn-Y-Nd-Zr Magnesium Alloys

With the advent of the information age,industrial technology has developed rapidly,and the types and quantities of electronic products have rapidly increased.Electromagnetic waves generated by related electronic information equipment are flooding every corner of people's daily lives.The electromagnetic energy that can be monitored in space is also increasing every year with a rapid growth rate of more than7%,excessive electromagnetic radiation will adversely affect people's normal production and life.Electromagnetic shielding is an effective means to solve excessive electromagnetic radiation.The development and research of new high-performance electromagnetic shielding materials has become the research focus of various countries.Magnesium alloy is now the third most widely used metal material after steel and aluminum alloy.It has lighter weight and good electromagnetic shielding performance,and is a new type of electromagnetic shielding material with great potential.However,the absolute strength of magnesium alloy is relatively low.This limits the application of magnesium alloys in the field of related structural materials.Therefore,it is of great significance to improve the mechanical properties of magnesium alloys and to develop new magnesium alloy electromagnetic shielding materials with higher strength and excellent electromagnetic shielding properties.In this paper,Mg-6Zn-1Y-x Nd-0.5Zr and Mg-6Zn-1Nd-x Y-0.5Zr series magnesium alloys were prepared by compounding Y and Nd on the basis of Mg-Zn-Zr magnesium alloy,and by changing the addition amount of rare earth elements.The electromagnetic shielding performance and mechanical properties of this series of magnesium alloys under different deformation states and thermal treatment conditions were studied,and the performance was improved by exploring the heat treatment system and improving the deformation process.The effects of changes in the content of rare earth elements of Y and Nd on the secondary phase structure,electromagnetic shielding performance and mechanical properties of the alloy were studied.The main research results are as follows:(1)The main second phase in this series of Mg-6Zn-1Y-x Nd-0.5Zr magnesium alloys includes:Mg-Zn-RE phase,a small number of Zr-containing particle phases and Mg-Zn phase.The main Mg-Zn-RE phase of the alloy Mg-6Zn-1Y-0.5Zr without Nd addition is Mg₃Zn₃Y₂(W phase).After the addition of Nd,Nd atoms replace part of the Y atoms to form a new W phase Mg₃Zn₃(Y,Nd)₂.The aged alloy Mg-6Zn-1Y-x Nd-0.5Zr has good electromagnetic shielding performance.With the addition of Nd element,the alloy's electromagnetic shielding performance improves.The aging state Mg-6Zn-1Y-1Nd-0.5Zr has the best electromagnetic shielding performance,which can reach 78-110d B in the test frequency range.(2)The extruded bar Mg-6Zn-1Y-x Nd-0.5Zr has high mechanical properties,and the strength can be further improved after aging.The mechanical properties of alloy Mg-6Zn-1Y-0.5Nd-0.5Zr in both extruded and aged state are the best.After aging,the yield strength is 386MPa,the tensile strength can reach 421MPa,and the elongation rate is 9.8%.The structure of the extruded alloy is a typical bimodal structure,consisting of coarse unrecrystallized grains and fine recrystallized grains.The addition of Nd refines the crystal grains,and the resulting Mg-Zn-RE phase can be used as a nucleation site for dynamic recrystallization to promote dynamic recrystallization.(3)The main second phase in the Mg-6Zn-1Nd-x Y-0.5Zr alloy includes the Mg-Zn-RE phase,a small number of Zr-containing particle phases and the Mg-Zn phase.There are two Mg-Zn-Nd phases in the alloy Mg-6Zn-1Nd-0.5Zr without Y addition,namely W phase and T phase.After adding Y element,Y atom and Nd atom together form Mg₃Zn₃(Y,Nd)₂phase.And the atomic ratio of Y and Nd in the Mg₃Zn₃(Y,Nd)₂phase will vary with the added elements.The aged alloy Mg-6Zn-1Y-x Nd-0.5Zr has good electromagnetic shielding performance.The electromagnetic shielding performance of the alloy increases with the increase of the Y content.The electromagnetic shielding performance of the alloy Mg-6Zn-1Nd-1.5Y-0.5Zr is the best,which can reach 76-106d B in the test frequency range.(4)The Mg-6Zn-1Nd-x Y-0.5Zr alloy extruded bar is still a bimodal structure composed of recrystallized grains and non-recrystallized grains.The mechanical properties after extrusion and aging have been greatly improved.The mechanical properties of the Mg-6Zn-1Nd-0.5Y-0.5Zr alloy in the extruded and aged states are the best in this system.The peak-aged yield strength is 365MPa,the tensile strength is392MPa,and the elongation is 6.6%.The addition of Y element refines the grains,promotes dynamic recrystallization,weakens the texture,and has an important effect on improving the properties of the alloy.