Study On Microstructure And Mechanical Properties Of Al/Mn Alloyed Mg-3Nd Extruded Alloy

Mg-RE alloys are widely used in new energy vehicles,aerospace and other lightweight fields due to their excellent comprehensive properties.In order to meet the needs of various industries for Mg-RE alloys,researchers have carried out a lot of research on high-performance Mg-RE alloys.It is well known that the properties of magnesium rare earth alloys can be effectively improved by alloying of various elements and deformation processing.Alloying can improve the properties of magnesium alloys by optimizing the microstructure ofthe alloy and changing the type and morphology ofthe second phase.At the sametime,the deformed magnesium alloy not only has uniform microstructure,fine grains,resulting insignificant improvements in strength and ductility,but also eliminates defects in casting.In this study,in order to develop low-cost and high-performance wrought Mg-RE alloy,the Mg-Nd-Al-Mn alloy was designed based on Mg-Nd alloy with the addition of Al and Mn.And the studied alloy was processed by hot extrusion deformation to further improve its comprehensive performance.The effects of Aland Mn alloying on microstructures and mechanical properties of Mg-3Nd alloy were studied by means ofvarious analysis and testing methods.the results are as follows:The addition of Al element refines the grains ofas-cast Mg-3Nd alloy.The second phase of the alloy is transformed from Mg12 Nd phase to Al11Nd3 phase and Al2 Nd phase.The as-cast Mg-3Nd-3Al alloy has the best mechanical properties,and the tensile strength,yield strength and elongation are 204.6 MPa,75 MPa and 13.5%,respectively.After hot extrusion deformation of the alloy studied,the grain size decreases with the increase of Al content,and the degree of dynamic recrystallization increases significantly,which weakens the texture,and the texture strength decreases from 9.70 to 4.64.The mechanical properties of as-extruded Mg-3Nd-3Al alloy are the best,with tensile strength,yield strength and elongation of283.9 MPa,192.1 MPa and 15.7%,respectively.Mn alloying refined the grains of as-cast Mg-3Nd-3Al alloy and formed Al10Nd2Mn7 phase.The as-cast tensile strength,yield strength and elongation increased to 224 MPa,79.3 MPa and 14.2%,respectively.The extruded alloy precipitates nano-sized particles composed of Al,Mn and a small amount of Nd elements,and the grain size is reduced.The effect of nano-sized particles on dynamic recrystallization and grain growth is the main reason for the increase in texture strength of Mn-containing alloys.The addition of Mn improves the strength and ductility ofthe extruded Mg-3Nd-3Al alloy.The tensile strength,yield strength and elongation ofthe extruded Mg-3Nd-3Al-0.5Mn alloy are 296.2 MPa,212.5 MPa and 18.3%,respectively.