Effect Of Yttrium Addition On Microstructure And Properties Of 7085 Alloy And Thermal Simulation Studies

On the basis of 7085 aluminum alloy smelting RE-7085 aluminium alloy,by adding different content of rare earth Y.The effects of Y on the microstructure and mechanical properties of 7085 aluminium alloy,and its microstructure was observed by OM,SEM and TEM.Then the result of test is analyzed and discussed.Flow stress of different temperatures and deformation rate on RE-7085 aluminium alloy were investigated by means of the isothermal compression test.Finally,the constitutive equation for flow stress of RE-7085 aluminum alloy at high temperature and the critical condition of its dynamic recrystallization has been established by linear regression.The main results of this study are as follows:The micro-alloying of 7085 aluminum alloy results show that the a-Al were refined with the addition of Y,while secondary dendrite arm space were obviously reduced and the grain boundary eutectic phase become fishbone structure.Y,Al and Cu form intermetallic compound Al3Y and A12Cu phase.Those phases distributes along the grain boundary.Adding rare earth additives in 7085 aluminum alloy can improves not only microhardness of alloy but also tensile properties at room temperature of the as-cast aluminium alloy.But the conductive properties of the alloy has a negative effect.In the compression quantity was 50%,the deformation temperature is 350? to 450?,strain rate of 0.1 s-1 to 5s-1 condition,thermal simulation experiment results of RE-7085 aluminium alloy show that the new material appears positive strain rate sensitivity.True stress-true strain curve of RE-7085 aluminium alloy under higher temperature and lower strainrate(?=0.1s-1,450?),the curves expressed the feature of dynamic recrystallization;under higher strainrate(?=1s-1,?=5s-1),the curves expressed the feature of dynamicrecovery.The thermal deformation activation energy of RE-7085 was measured,which is 175KJ/mol.RE-7085 according to the thermal deformation of microstructure,rare earth Y can significantly inhibit deformation of 7085 aluminum alloy dynamic recrystallization crystal grains grow up under high temperature in the process;The number of dynamically recrystallized grain increased with the deformation temperature increasing and strain rate decreasing.But the recrystallization grain size shows litter change.