Microstructure And Mechanical Properties Of The As-extruded Mg-Zn-RE(Y,Gd,Nd) Alloys

With the energy crisis and the deterioration of the environment,people began to find some new materials to replace the conventional iron and steel materials,And magnesium alloy is the lightest metal structural material,coupled with its own specific strength,high specific stiffness,good anti compression,anti-impact performance and other advantages,Make it widely used in aerospace,automobile and other fields.At present,the mechanical properties of magnesium alloy are mainly concentrated in the quasi-static mechanical properties,but the mechanical properties of the high strain rate of magnesium alloy are also still relatively little.In this paper,the mechanical properties of magnesium alloys with different high strain rates are studied by electro-hydraulic servo high-speed tensile testing machine(Zwick/Roell Amsler HTM5020).In this paper,the microstructure components of the as-extruded Mg-Zn-Y,Mg-Zn-Gd,Mg-Zn-Nd alloys were analyzed by optical microscope and scanning electron microscopy,X ray diffraction and TEM,Then,the tensile test of the magnesium alloy was carried out by universal tensile machine and high-speed tensile machine,and get the quasi-static tensile properties and the high speed tensile properties of the alloys and make a contrast analysis.The results obtained are as follows:(1)The dynamic recrystallization occurred during the extrusion,at 300 ? and extrusion ratio was 16,the grain size was refined,and the second phase particles in the alloy were distributed along the extrusion line.(2)In the Mg-Zn-Y alloys,the strengthening phase of the Y0.49 alloy is I phase and Z phase distribution along the extrusion direction.The average grain size of Y0.8 alloy is 2.35?m,the effective reinforcement phase is H phase and dispersion distribution of W phases along the extrusion direction.The average grain size of Y1 alloy is 5.01 ?m,the effective reinforcement phase is I phase and Z phase.(3)The average grain size of Gd0.49 alloy in the Mg-Zn-Gd system is 5.20?m,and the effective reinforcement phase is H phase along the extrusion line.The average grain size of Gd0.8 alloy is 1.91?m,the effective reinforcement phase is H phase and 14H phase.The average grain size of Gdl alloy is 4.99?m,the effective strengthening phase is W phase,the average grain size of Gdl.2 alloy is 5.19?m,and the effective reinforcement phase is I phase and Z phase.(4)The average grain size of Nd0.8 alloy in the Mg-Zn-Nd system is 2.08pm,and the effective reinforcement phase is H phase along the extrusion line.(5)At room temperature,strain rate from 10-3/s-417/s.With strain rate increasing,the alloy of yield strength and tensile strength were increased,but the extension of the alloy rate first decreased and then increased.(6)Under the same conditions,the Y0.8 alloy in the Mg-Zn-Y alloys with maximum yield and tensile strength,the Gd0.8 alloy in the Mg-Zn-Gd alloys with maximum yield and tensile strength at high strain rate,but at quasi static state Gdl.2 alloy have the maximum strength,then in all the alloys Nd0.8 alloy own the elongation rate.