Preparation And Deformation Behavior Of Mg-Al-Y Alloy

In this article,we adopt CO₂ and SF₆ gas protection to prepare Mg-Al-Y alloy in crucible furnace,using extrusion machine,rolling mill,Instron-5982 universal testing machine,metallographic microscope,X-ray diffraction（XRD）,scanning electron microscope（SEM）,etc.The microstructures,room temperature mechanical properties,and deformation textures of as-cast,extruded and rolled alloys were studied and analyzed.The evolution of microstructures at room temperature was studied by using electron backscatter diffraction（EBSD）.The as-cast Mg-1Al-xY（x=3,5,8）alloys consist ofα-Mg phase and Al₂Y phase.Among them,the primary Al₂Y phase is in a massive distribution with large size and uneven distribution,which has an adverse effect on the microstructure and properties of the alloys.The eutectic Al₂Y phase distributes in the form of grains or strips in the structure and acts as a dispersion strengthening.With the increase of Y content,the number of precipitates gradually increases,and there is a clear cleavage step at the tensile fracture at room temperature,and the fracture mode changes from cleavage fracture dominated by cleavage to cleavage fracture,brittle fracture of Al2Y phase,and ductile fracture.The as-extruded Mg-1Al-xY（x=3,5,8）alloys are composed ofα-Mg phase and Al₂Y phase and the alloys structure are basically a dynamic recrystallized structure,in which the Mg-1Al-5Y alloy has a tensile strength of316MPa at room temperature,the yield strength is 150MPa and the elongation is 17%.The tensile strength of Mg-1Al-8Y alloy is 288MPa at room temperature,the yield strength of 174MPa and the elongation of 20%.Its have good mechanical properties and the fracture mode of alloys are ductile fracture dominant fracture mechanism.The as-rolled Mg-1Al-xY（x=3,5,8）alloys are composed ofα-Mg phase and Al₂Y phase.With the increase of Y content,a large amount of twins appear in the microstructure,Comprehensive mechanical properties increase with increasing Y content,The Mg-1Al-8Y alloy has a tensile strength of 290 MPa,a yield strength of125 MPa and an elongation of 8.3%.The macro-texture of the as-extruded alloy and the as-rolled alloy were analyzed by X-ray diffraction.The extruded alloys are（0002）basal fiber texture,and the（0002）based panel texture were formed by the as-rolled alloys.With the increase of Y content,the texture strength of the alloys decreased,but the type of texture did not change.The extruded Mg-1Al-8Y alloy was annealed and in-situ tensile deformation tests were performed at room temperature.The microstructure of the as-extruded Mg-1Al-8Y alloy was observed and analyzed with EBSD technique.The results showed that the slip was the tensile deformation of the extruded alloy at room temperature.The main deformation mechanism in the process,while the twin mechanism contributes little to the deformation.