Study On Microstructure And Properties Of Mg-Li Binary Alloy Prepared By Centrifugal Casting

Mg-Li alloy is currently the lightest metal structural material,with high specific stiffness and specific strength,good plasticity,good seismic performance and high-energy grain penetration resistance,etc.Sports equipment,3C industry,passenger vehicles,medical and electronic fields have broad application prospects.(α-Mg + β-Li)The α-Mg phase in the dual-phase Mg-Li alloy is beneficial to increase its strength,while the β-Li phase is beneficial to improving its plasticity.The composite structure formed endows the dual-phase Mg-Li alloy with relatively excellent comprehensive mechanical properties,and the dual-phase Mg-Li alloy is the current research hot spot.In a two-phase alloy,the difference in the content,distribution,and morphology of the two-phase structure will lead to differences in the macroscopic properties of the alloy.In this experiment,the Mg-Li binary alloy material with gradient structure was prepared by centrifugal casting,and the alloy was cold-rolled.The microstructure and mechanical properties of the centrifugally cast and cold-rolled modified alloy were systematically analyzed.This study reveals the influence of the two-phase structure matching relationship,such as the content and distribution of the two phases,on the macroscopic mechanical properties and formability of the alloy,which has important guidance for the subsequent microstructure design and mechanical property control of the two-phase Mg-Li alloy significance.Through the research in this article,the following conclusions are mainly obtained:(1)The microstructure of the Mg-8.5Li binary alloy in the centrifugally cast state of 300r/min,600r/min and 900r/min and the 50% cold-rolled modified form are all gradient changes along the increasing direction of the centrifuge radius As the radius increases,the volume fraction of α-Mg phase gradually increases,and the volume fraction of β-Li phase gradually decreases.When the centrifugal speed increased from300r/min to 600r/min,this gradient change rule became more obvious;when the centrifugal speed increased from 600r/min to 900r/min,this gradient change rule decreased.(2)The tensile strength and yield strength of the 300r/min,600r/min and 900r/min centrifugally cast and 50% cold-rolled modified Mg-8.5Li binary alloys gradually increase along the direction of increasing centrifugal radius The gradient of the gradient changes,the elongation of the centrifugally cast alloy in the direction of the increase of the centrifugal radius is generally gradually increasing gradient change law,the cold rolling deformation form elongation has no change.The mechanical properties of the50% cold-rolled deformed Mg-8.5Li alloy by centrifugal casting are better than the corresponding Mg-8.5Li alloy at the same speed,except for the cold-rolled 600r/min near-center end.Below the corresponding casting state.Cold rolling deformation can maintain the gradient of the mechanical properties of the centrifugally cast state and improve the mechanical properties of the alloy,but it cannot improve the elongation.(3)Compared with gravity casting Mg-8.5Li alloy,the tensile strength,yield strength and elongation of centrifugally casting Mg-8.5Li alloy have been improved,of which 900r/min centrifugally casting Mg-8.5Li alloy has The tensile strength and elongation were increased to 142 MPa and 18.8%.Compared with gravity casting 50%cold-rolled deformed Mg-8.5Li alloy,centrifugal casting 50% cold-rolled deformed Mg-8.5Li alloy has improved tensile strength and yield strength,and the elongation is basically reduced,of which 600r/min The centrifugally cast 50% cold-rolled deformed Mg-8.5Li alloy has a tensile strength of 211.2 MPa and an elongation of 7%.(4)During the centrifugal casting process,the melt is subjected to the combined action of centrifugal force,viscous force,repulsive force and excitation force,which causes the solute in the melt to segregate and segregate,causing the gradient of the alloy structure to change.The growth of dendrites is suppressed,the number of spontaneous nucleation and the number of grains increase,and the grains are refined,thereby improving the overall performance of the alloy.The distribution of α-Mg phase and β-Li phase in the alloy has an important influence on the mechanical properties of the alloy.When the α-Mg phase increases and the β-Li phase decreases,the mechanical properties of the alloy increase,and vice versa.