Microstructure And Performance Of New Mg-Er-Y-Zn-Mn Alloy

Adding rare earth(RE)elements to Mg alloys is very effective in improving the mechanical properties of magnesium alloy.Mg-RE-Zn containing RE-deformed magnesium alloy is a common material,its microstructure and mechanical properties mainly depend on the proportion of Zn and RE.In this paper,two new high performance Mg-ErY--Zn-Mn alloys were successfully prepared by alloy design and process control,and the viewpoint that the base stacking fault precipitation phase at high temperature has better enhancement effect than cylindrical precipitation is put forward.The innovative research of this work is beneficial to the development of high performance deformed magnesium alloys and expands their application range.For the first time,a single high-number density base stacking fault stacking layer dislocation(Mg-6Er-3Y-1.5Zn-0.4Mn(wt.%))enhancement was prepared in deformed magnesium alloys(EZ92),a new idea of composite reinforcement of various enhanced phase(SFs+LPSO+W)is proposed,and this new alloy is designed and prepared,Mg-4Er-2Y-3Zn-0.4Mn(wt.%)alloy(EZ63).Both alloys are microscopic tissues of mixed crystals(recrystallization fine crystals + deformed crystalline coarse crystals).The as-extruded EZ92 alloy of the special tissue with single high number density base stacking faults(SFs)is enhanced,which has higher high temperature strength than the current reported heat-resistant magnesium alloy,and has higher thermal conductivity.After thermal extrusion deformation,the yield strength and tensile strength of EZ92 alloy along extrusion direction are 311 MPa,353 MPa,respectively,and when the temperature reaches 300 ?,the yield strength of the alloy is 271 MPa,and the tensile strength reaches300 MPa.The excellent high temperature performance is mainly due to the nano-interval of the base stacking fault and the 1~2?m fine grains with large aspect ratio in the whole matrix,as well as the many small angle grain boundary and the higher base stacking fault texture in the recrystallization grain.Unlike EZ92 alloy,the as-extruded EZ63 alloy not only has high density SFs,but also has the nano-particle W phase and the LPSO phase dispersed in the recrystallization region,and the yield strength and tensile strength at 250 ? are 251 MPa and264 MPa,respectively.The thermal conductivity of the alloy increases with the temperature,and the thermal conductivity of the extruded alloy is lower than that of the cast alloy.The thermal conductivity of the as-extruded EZ92 alloy and EZ63 alloy at 300 ? is 73 and 86W/(m?K)respectively,which is a relatively high value for high strength mg-re alloys.