Microstructures And Properties Of AZ80 Magnesium Alloy With La And Gd Addition

Magnesium alloy is the lightest metal structural material by far,and has good overall performance,with high specific strength and specific stiffness,high thermal conductivity,easy recycling,good damping properties,good electromagnetic shielding effect,etc.,in aerospace,automotive,3C products and other fields have a wide range of applications,but the absolute strength of magnesium alloy is not high,which is one of the major obstacles hinder its large-scale application.AZ80 is a typical high-strength industrial magnesium alloy,but because of its large amount of low melting point eutectic phase,narrow window of plastic deformation,at the same time,its heat resistance is poor.Therefore,La and Gd rare earth elements were further added into the AZ80 magnesium alloy and their extrusion deformation was carried out.The effects of the primary extrusion state,the secondary extrusion state and the aging treatment on the microstructure and mechanical properties were studied.Conducted on its conductivity,draw the following main conclusions:(1)When the AZ80 is extruded at a lower temperature(<230?)(the extrusion speed is 0.2mm/s and the extrusion ratio is 24.3),the strength of AZ80 increases with the increase of extrusion temperature,but the elongation have little changed.When the alloy is extruded at 230?,the mechanical properties are the most uniform and the mechanical properties are the best.The maximum tensile strength is 317MPa,the yield strength is 223.1 MPa and the elongation is 13.9%.After aging treatment,Mg17Al12 phase precipitates,the room temperature strength of the alloy increases,the plasticity decreases,the tensile strength reaches 333.4MPa,the yield strength reaches 233.8MPa and the elongation is 8.6%;(2)When the AZ80 is extruded at a lower temperature(280?),a faster speed(1mm/s),due to extrusion speed,uneven deformation,resulting in uneven microstructure,mechanical properties are poor;When AZ80 was extruded at higher temperature(330?)and slower speed(0.5mm/s),the deformation of the AZ80 was uniform and the mechanical properties were better.The tensile strength reached 319MPa,the yield strength reached 221.6MPa,the elongation was 14.8%;(3)AZ80 with different once extrusion conditions had higher plasticity after secondary extrusion deformation,but the strength decreased.With the secondary extrusion temperature increases,the strength of AZ80 with the same once extrusion conditions is on the rise,but the plasticity decreased.When the secondary extrusion at 330?,the alloy has the best mechanical properties,the tensile strength is 311.5MPa,the yield strength is 204.7MPa and the elongation is 16%.After aging treatment,Mg17Al12 phase precipitates,the room temperature strength and the ductility of the alloy increased,the tensile strength reached 325.8MPa,the yield strength reached 221.5MPa and the elongation rate was 10.6%;(4)The conditions of extrusion and secondary extrusion have no obvious effect on the electrical conductivity of AZ80.T5 aging treatment can greatly improve the electrical conductivity of the alloy,mainly due to the precipitation of a large amount of ?-Mg17Al12 phase to reduce the solid solution in the matrix Atomic content,lattice distortion weakened,thereby reducing its impediment to electron mobility.