The Effect Of Rare Earth Y And Gd On The Structure And Corrosion Resistance Of AM60B Magnesium Alloy

Magnesium alloy has the advantages of high strength,light weight and resource-rich,which fully meet the requirements of lightweight in industry.However,poor corrosion resistance of magnesium alloy has always been a problem,which also limits its engineering.At the present stage,the research on the corrosion performance of Mg-Al-Mn alloy is not complete,there are many studies which study on the mechanics performance or corrosion performance of magnesium alloy,but very few studies combine them.When use magnesium alloy in practice,both the mechanics performance and corrosion performance should be take into consideration,so it’s significative to ensure the good mechanics performance while study the influence of Y and Gd on the corrosion performance of Mg-Al-Mn alloy.On the basis of previous studies,this paper analyzed the composition optimization of as-cast alloy AM60B by adding different contents of rare earth Gd and Y,and designed magnesium based rare earth alloy AM60B-RE with reasonable composition.And conducted the tensile properties,electrochemical performance test,salt water immersion test on both as-cast alloy and alloy after solution treatment,and observed the effects of rare earth elements and solid solution treatment on the microstructure of AM60B with the aid of optical microscope,scanning electron microscope,X-ray diffraction,transmission electron microscopy,and discussed the influence mechanism of Gd and Y and solid solution treatment process on AM60B alloy mechanical properties and corrosion resistant performance.The results showed that Y and Gd can improve the mechanics performance and corrosion performance of AM60B,but they showed different laws.The addition of Y and Gd can effectively refine the grain size and optimize the matrix organization,thus improve the mechanics performance and corrosion performance of AM60B.But when rare earth content is more than 1.4%Gd+0.2%Y,the mechanical properties of alloy began to decline,when the content of Y beyond 0.5%,alloy corrosion resistance began to fall,as the Y content continues to increase,corrosion resistance and mechanical properties of the alloy gradually decline,when Y content reaches 1.1%,When Y content reaches 1.1%,a large amount of rare earth compounds appear in the alloy,divided the matrix into uneven parts,and the large amount of rare earth compounds will act as a cathode to accelerate the corrosion of theα-mg matrix,resulting in a decline in the mechanical properties and corrosion resistance of the alloy.After 12 hours 410℃solution treatment,mechanics performance and corrosion performance of the alloy got improved,the tensile strength of AM60B with 1.4%Gd and 0.2%Y after solution treatment came to 266.49 Mpa,was highest in all alloy,and it’s elongation was 11.3%.AM60B with 1.4%Gd and 0.5%Y had the best corrosion performance,its’self-corrosion potential was-1.356V,its’corrosion current density was 0.025mA/cm~2.AM60B with 1.4%Gd and 0.2%Y had the best combination property,its’tensile strength was 266.49Mpa,elongation was 11.3%,self-corrosion potential was-1.401V,corrosion current density was0.068mA/cm~2.Solution treatment can refine the grain and make the solute distribution in the matrix more uniform,so as to improve the mechanics performance and corrosion performance of AM60B-RE.However,due to the good thermal stability of rare earth compounds,solution treatment had not solved the degradation of mechanics performance and corrosion performance caused by the polymerization of rare earth compounds.