Long-period Structural Evolution And Mechanical Properties Of Mg-Zn-Y Alloys

Magnesium alloy has the characteristics of low density and high specific strength,and is widely used in automotive,electronics,aerospace and other fields.In recent years,through the in-depth study of magnesium alloys,it is believed that Mg-?Cu,Zn,Ni?-RE alloys can generate a special long-period ordering?LPSO?structure.This structure of magnesium alloy material has a good organization.And mechanical properties,can effectively improve the performance of magnesium alloys.Therefore,by adjusting the types and composition ratios of alloying elements in magnesium alloys or by adding appropriate amount of rare earth elements,the relationship between the long-periodically ordered stacking structure and the composition of alloys and their laws are studied.The application of magnesium alloys has important theories.Meaning and practical value.In this experiment,a new type of Mg-Zn-Y alloy containing a long-cycled ordered structure?LPSO?was prepared by a casting and heat treatment process.By analyzing the formation and strengthening effect of the LPSO structure of the alloy,alloying elements were studied.The effects of rare earth elements on the formation and transformation of long-period structures and their effects on the mechanical properties of alloys.Studies have shown that LPSO structure can enhance the mechanical properties of the alloy.When the heat treatment time of Mg-2.5Zn-6.8Y alloy was500°C for 10 h,the mechanical properties of the alloy were the best,and the elongation and tensile strength were 5.1%and 149 MPa,respectively.When the alloy was heat-treated at 500°C for 10 h,the LPSO structure was solid-solved in the matrix and significantly refined.The addition of Al in Mg-Zn-Y alloy improves the properties of the alloy.After adding Ag,the degree of refinement is obvious.Ag element can affect the overall distribution and morphology of LPSO phase to some extent.In the Mg-Zn-Y-Al alloy,the Al element has a certain strengthening effect on the alloy and improves the mechanical properties of the alloy.When the content of aluminum in the alloy was 1%,the alloy exhibited better mechanical properties,and the elongation and tensile strength were 5.4%and 176 MPa,respectively.After adding Ag in Mg-Zn-Y alloy,the grains of the alloy were refined,most of the second phase of the alloy precipitated along the grain boundaries,and a small amount of Mg₃Ag phase was formed.It is mainly distributed at the grain boundary,which can effectively prevent the grain boundary from sliding during plastic deformation and hinder the movement of dislocations,and improve grain boundary stability and tensile strength.When Ag content is 3%,the tensile properties and ductility of the alloy are good,and the tensile strength and elongation are 194 MPa and 7.1%,respectively.When the Ag content is 2%,after aging treatment at 200°C,the duration of 24 h,the best microhardness of the alloy is 81.2 HV.