Analysis Of Microstructure And Mechanical Properties Of Mg-Zn-Y Alloy

Magnesium alloys have been recognized as the most promising lightweight materialsand green metallic materials in the twenty-first century because of its light weight,durability, shock absorption, recyclable, and many other advantages. It will have a hugemarket after Aluminum alloy. And its application has a bright future. As a structuralmaterial, some disadvantages of the magnesium alloy are the important reason for itsapplication restriction. In order to provide theoretical and practical basis for the practicalapplication of new magnesium alloys, the microstructure and mechanical properties ofMg-Zn-Y alloy has been studied in this paper.Four kinds of Mg94.5Zn4.3Y1Zr0.2、Mg77.9Zn18.5Y3.1Zr0.5、Mg82Zn14.2Y3.3Zr0.5and Mg94.8Zn4Y1Zr0.2alloy were designed and prepared in the present study. The microstructure and mechanical properties of the alloy were mainly investigated， by analytic methods, such as optical microscopy (OM),scanning electron microscopy (SEM) and X-ray diffractometer (XRD) etc. and by physical property measurements of materials, such as hardness etc.The results showed that at the same holding time, diffuse precipitated phases becomethin with the increase of temperature, tending to form the shape of point and short bar;Under the same temperature conditions, number of diffuse precipitated phases at grainboundary increased significantly with the increase of holding time. After500solid solution,at270℃and320℃temperature limitation, in a certain period of time as the agingtime,the size of dendrites in the alloy became more fine, Cast reunite of diffuseprecipitated phases still distributes in the grain boundary. When the holding time is24h,diffuse precipitated phase became the shape of dispersive short rod and linear, distributing more evenly in the crystal, the number increased gradually.After the holding time of48h,alloy internal grain structure of alloy had changed, intragranular precipitates presentthe trend of globalization; Under the condition of holding time of24h at270°C and320°C,the alloy has higher hardness because of a lot of quasicrystal I phase at grain boundary andinside.Therefore the conditions for processing system is more reasonable. In addition toheat treatment, the Zn/Y and the content of the Zn and yelements have a great relationshipto the effect of the quasicrystal content in Mg-Zn-Y alloy. The content of quasi crystal inZn/Y ratio close to the content of5-7.After a test showed that,increase the content of Znand Y two elements in the alloy,quasicrystal will increase.