| Magnesium alloy is the lightest structural metal materials,it has a series of excellent features(Thermal conductivity,stiffness,high specific strength higher),This makes it the hottest of hot material in many fields.However,shortcomings in conventional magnesium alloys such as low high temperature strength,poor corrosion resistance has seriously hindered its further development and application in industry.Studies have shown that alloying of rare earth elements can improve the overall performance of magnesium alloys.The rare earth metals have high chemical activity,there are so much differences of melting point and density of compared to the magnesium alloys,so rare earth elements can not be added directly to magnesium alloy as the form of element.Rare earth metals will be severely burning and segregation,material waste,increased costs.In order to be ensured a fully functioning,the rare earth elements usually added in the form of RE magnesium alloy intermediate.RE-Mg master alloy have different preparation processes.In order to understand the impact of RE-Mg master alloy preparation process on magnesium alloy,in this paper,the rare earth element gadolinium,yttrium and AZ91 D magnesium alloy were used as the research object.Methods of mix-melting method and molten salt electrolysis were adopted in preparation of the Mg-Gd / Y master alloys,and then add these master alloys to the AZ91 D alloy to get AZ91D+1Gd/Y applications alloys.Composition and content of the alloy were tested by the method of XRD,ICP and OM.Microstructure and phase composition of the alloys have be analyzed.Analyzing the morphology of the alloy microstructure and microanalysis was by scanning electron microscopy(SEM)with energy dispersive spectrometer(EDS).Alloy hardness testing,tensile strength and elongation was by Vickers hardness tester,electronic tensile testing machine.Corrosion of the alloys were tested and analyzed by CS350 electrochemical workstation,the experimental results were analyzed and discussed.The main contents and results of this article are as follows:(1)Master Alloy was prepared by Melting method.The melting time of two alloys respectively 30 min,35min,40 min.The alloys were Mg-Gd a,Mg-Gd b,Mg-Gd c,Mg-Y a,Mg-Y b,Mg-Y c.Mg-87 Gd master alloy was prepared by molten salt electrolysis method,and then add Mg metal melted to Mg-20Gd(Mg-Gd d).(2)The seven kinds of master alloy were added to AZ91 D alloy according to certain proportion with vacuum melting method.Prepared by the AZ91D9+Gd a ? AZ91D9+Gd b ?AZ91D9+Gd c?AZ91D9+Gd d?AZ91D9+Y a?91D9+Y b?AZ91D9+Y c.(3)By analyzed the composition and organization of master alloy Mg-Gd(a,b,c,d)andMg-Y(a,b,c),it was found that,Gd content decreased and Grain size increments with the growth of the melting time on Mg-Gd(a?b?c)alloy,Gd content is highest and the grain size is least.the Y content after decreases and then increases,the grain size after first reducing and then increases on Mg-Y(a?b?c).(4)By study the microstructure,mechanical properties and corrosion resistance of alloys which were prepared such as AZ91D+Gd(a?b?c?d)?AZ91D+Y(a?b?c)and AZ91 D alloy,we found that AZ91 D performance has improved to some extent after adding Gd,and Y.The overall performance of AZ91 D + Gd(a,b,c)decrease with the growth of the added intermediate alloy melting time,the overall performance of AZ91D+Gd d is the best.The overall performance of AZ91D+Y(a?b?c)rise after the first drop with the growth of the added intermediate alloy melting time. |
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