Research On Microstructure And Texture Evolution Of Mg-Li Alloy During Rolling And Annealing

As the lightest metal structural material in service,Mg-Li alloy has low density,high specific strength and specific stiffness,and good recyclability.It is highly suitable for energy conservation,environmental protection and green development,and has been listed among the hot research materials.This subject uses optical microscropy(OM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD)to test and analyze the evolution of the microstructure and texture of the as-cast ? single-phase Mg-4.5Li and?+? dual-phase Mg-8Li alloys and extruded states ?+? dual-phase Mg-8Li alloy after rolling and annealing,to explore the deformation mechanism of Mg-Li alloy during processing.The results indicate:(1)Different types of twinnings,mainly {10 (?) 2} tensile twinning and{10(?)1}-{10(?)2} secondary twinning appear in the alloy after rolling deformation,the deformation first occurs in the ? phase and then in the ? phase,and static recrystallization occurs after annealing.The evolution of microstructure and distribution is closely related to the initial state and the direction and magnitude of the applied load.(2)The texture evolution of the as-cast Mg-4.5Li alloy and Mg-8Li alloy during rolling and annealing is similar,and the grain orientation changes from a random state to a bimodal texture deflected along the RD as the rolling variable increases.The difference is that the circle texture appears in Mg-8Li and there is no obvious change after annealing.(3)Homogenization has an effect on the evolution of the texture after annealing,and the initial texture has no or little effect on the evolution of the texture.(4)The bimodal texture is the result of the combined action of base slip,pyramidal<c+a> slip and {10(?)1}-{10(?)2} secondary twinning.The decrease in deflection angle is the result of competition between base slip and pyramidal <c+a> slip,the activity of pyramidal <c+a> slip decreases as the rolling variable increases.The two reach a balance at a deflection angle of ±20°,and the cyclic texture component is considered to be caused by the initiation of prismatic slip.(5)When the extruded Mg-8Li alloy is deformed by secondary rolling along RD',the ?-phase texture composition remains unchanged,and only changes in strength,which can be attributed to the body-centered cubic structure of ?-phase.